Hello everybody! Quick question.

What do you do to spice up Dungeons? When my group is out in the wildmy description seem to work really well and everyone knows what to do. In dungeons I seem to either overdescribe or underdescribe the rooms. Which tends to sometimes dragging room explorations since everyone wants to know what is under that bed and I open that door very slowly. So how do you do it? How can I spice up the thing and keep it at a good pace?

We play very traditional with no tech devices. Just a map, a pen and miniatures. I went from drawing the whole dungeon as the discover it ot hand out prints of the rooms to now just drawing the rooms where they fight in.

So what do you do?

Start telling them that rummaging through the room is likely to cause noise and attract attention.  You can also start skipping rolls for some investigation and perception, so if they want to check through the bed just tell them they easily search it and find nothing. Sprinkle in rolls, even when there's nothing, now and again so they don't start to take a roll as an indication there must be something and they need to check better.

Players can often scout ahead and spoil a good deal of surprises as well, with a shape shifting druid or familiar flying or crawling on the roof and uncovering the whole dungeon at once.

The first strategy against this should be roadblocks.  These could be rubble covering a way, a large boulder or a simple door.  It limits their scouting so you actually have an opportunity to surprise them.  It might also be some sort of monster that will snap at, and eat, any tiny creature that tries to pass it.  A player might find it unbelievable that a humanoid soldier would be alarmed at a bird or spider, but its pretty easy to imagine a simple bat would eat a spider or a cat attack a bird.

The second strategy is hidden passages and hidden enemies.  So opponents that a scout might miss or a hidden nook that a lookout or set of guards keep watch from.  This can be great to surprise players who pass through an area carelessly because they believe it's clear from their scouting.  Unexpected combat is always a spice

The third strategy is traps.  Such scouting creatures aren't necessarily great at spotting traps and could easily not set them off if they're flying or crawling on the ceiling.  The traps can do different things beyond just injure someone as well, they could alert nearby enemies, trap one or more party members and require a puzzle like solution to get out OR block a path.  When a path is blocked by a trap, it could also split the party if some are on one side or another.  Suddenly, their scouted path or retreat could be unavailable and a split party might be in big trouble as it attempts to navigate back together or it might even initiate a combat encounter for both split groups that will suddenly be unable to support each other and require a puzzle or work to open the barrier.

Finally, moving monsters.  Just because the party scouted out where all the monsters are in that moment, doesn't mean the monsters can't move about the map of their own free will, even if they're unaware of the adventurer's presence the monsters might move.  You can also have monsters return from outside the dungeon and catch the players from behind.

This is where traps come in.  Its usually pretty easy for such creatures to miss traps, particularly if its the sort of

I actually don't think this is a behavior you want to discourage. It sounds like your players are having fun, and it sounds like they're buying into the world you've built them really well (which is the opposite problem many groups have).

If anything, I might encourage this behavior by sneaking treasure into one or two of those little crevasses they're always searching. Or notes. Think about how in Skyrim sometimes you find little journal entries in a bandit camp that tells you a little about who lives there and maybe where some extra gold or a magic item is stashed. Players love that kinda stuff. 

And if they really do start taking ten minutes to search *every* room and you want to speed things up, you can use subtle queues;

"You hear another thunderous booming sound from the caverns deep below. You don't know what's causing it but they've gotten more frequent since you've arrived."

"Passing a door, you hear echoing footsteps marching down the hall a ways-- sounds like a guard patrol will be here in a few minutes!"

Stuff like that to remind them they're in a hostile area and don't have a ton of leisure time. 

And finally, keep in mind what a room is being used for. Or, in the case of ancient crumbling fortresses, what a room used to be verses what its current occupants are using it for. Like, this room used to be a kitchen and the hobgoblins have been using it as a guardroom. Is there likely to be a ton of hidden treasure in either location? Probably not. But like, the giant spider made its main nest in the old master bedroom-- that sounds like an area more worthy of an extensive search. And if players don't pick up on it, you could always say offhand something like "well how many people store their treasure in the kitchen after all?" when they turn up nothing and they'll understand that you're applying that kind of logic to treasure location. 

Keep in mind that players can only “see” what you tell them is there. If you describe an object, it’s like you shining a spotlight on it and makes them think it’s something to investigate. The less frequently you describe things, and the more detail you give things, the brighter the light you shine on those things you do describe. 
So try and keep it consistent. If you say “this looks like it used to be a bedroom” every time, but then one time you say, “this room has an ornately carved, 4-post canopy bed.” What you are really saying is “look at this bed, it’s really important.” You can use that both for the party and as a misdirect.

So try to keep a consistent level of detail in each room they search. Then when you really need them to find something, you can give it some extra detail, and they’ll pick up on that clue. Conversely, you can occasionally describe things in detail that don’t mean much. The ornate bed is the most interesting thing in the room, but really, they should be looking through the pile of moth-eaten clothes in the corner because that’s where the sack of gold is. Or the spell scrolls which are tucked between books on the old, dust-covered desk.

A lot of good advice on here. One thing I might add is to consider the dungeon as an NPC and use it to worldbuild and establish tone to spice up the narration.

I personally have a hard time with immersion in dungeon crawls if the traps, puzzles, and monsters feel random or contrived. But when a dungeon has a theme and everything in it serves that theme, the exploration and obstacles seem to flow naturally. If I know I'm in an abandoned temple to the god of darkness, and a mural reminds me that secrets thrive in the dark, then I'm going to expect to use my darkvision, seek out shadows, and be prepared to encounter traps or monsters that react to light. With a pervasive theme, I have a clue about what to look for and what to ignore, and sparse details from the DM can help me avoid getting bogged down in irrelevant details.

Do you have to give every dungeon a theme? Definitely not. But having one, hinting one, or even creating traps and combat encounters with a motive/motif (such as "whoever built this wanted to trap infiltrators, not kill them" or "the mansion's owner loves dogs") can help players spot patterns more readily and not get as distracted by irrelevant details.

Limit how many investigation checks per thing. Either one roll at advantage with a second person helping, or two people can check. 

If it is really bogging down the game and the players are complaining that they are spending so much time searching every nook and cranny, have searches cover more areas. Instead of searching each wall separately and each object in the room go with one search of the room and one for checking the door for traps. 

Diseases and poisons from searching through filth can also cut back on extensive searches, although they will start using poles or mage hands instead of digging in directly.

A way to spice up your dungeon is by placing features in decor to be investigated like furnitures and use creatures with the False Appearance trait that springs surprise attack, such as mimic, flyring sword, smothering rug, table chair, knife etc.. as well as those with the Transparent trait such as Gelatinous Cube.

You can use flooded area of the dungeon filled with dark water 5 feet deep containing ooze creatures that go by unseen, such as black pudding, slithering tracker or yellow orche jelly.

Thank you all. This is really great an much appreciated. I will try to incorporate some of these tactics and test them. 

I reserve about a third of my dungeon/wilderness content to be plot-relevant, another third to be empty/nothing of interest, and the last third as "exploration for exploration's sake." Basically not featuring anything immediately useful but rather focused on building out the world or telling a story about a particular NPC or organization. Sometimes this information proves useful later (especially if the party engages with it and shows interest) while other times it just exists because the world is bigger than their story.

I see what you mean. I try to keep that in mind.