What is it that really scares a player? What is it that really engages a player?
When you run an adventure, you could sprinkle in Dungeon Dressing. ("here is a dead calm that is warm that smells like urine. The air is hazy with dust. You can hear sobbing and evil laughter in the distance. You find a pile of pottery shards and a cuboard here. You also see a scroll in the room." from here.) In an identical way, when running a horror module, you could sprinkle in horror dressing. ("The front doors slam behind you!")
But even though from almost the earliest documents, you could generate it randomly, it was never meant to be random.
Proof in the Pudding
Let's look at one of the best examples of classic play, the sample dungeon and transcript of play in the 1st edition Dungeon Master's Guide.
ENTRY CHAMBER: A damp and vaulted chamber 30' square and arched to a 20' high center roof. Arches begin at 8 and meet at a domed peak. Walls are cut stone black, floor is rough. Thick webs hide ceiling. See A & B below.Thick webs hide the ceiling, because spiders live there.
Heavy oak door with bronze hardware is remarkable only in that if any character listens at it, he or she will detect a moaning which will rise and then fade away. Unbeknownst to listeners, it is the strong breeze which goes through area 2. AS SOON AS THIS DOOR IS OPENED, A WIND GUST WILL EXTINGUISH TORCHES AND BE 50% LIKELY TO BLOW OUT LANTERNS AS WELL. The wind continues to make the corridor impossible for torches until the door IS shut.The moaning heard is caused by wind and directly affects play.
3. EMPTY CEREMONIAL CHAMBER: . . . A wooden platform, supposedly merely a dais for ceremony and religious rites, was placed against the south wall. This platform being 9’ off the ground enabled the use of the secret door in the south wall—this portal being 8’ wide, 10’ high, and 10' above the floor of the chamber. Amongst the 7 small protruding knobs of stone about 9' above the floor, the 7th pushes in to trigger the door mechanism, and the portal will swing inward (swings east) with a grinding noise. The only clue which still remains are socket holes in the south wall. There are 2 at the 20’ and 2 at the 30’ line (that is, on either side of the centermost 10’ south wall space). Each pair has 1 socket at about 4‘ height, 1 at about 8 . Each socket is 1/2 X 1/2 square and a little deeper. The first socket hole examined by the party will have several splinters of wood (from the platform, of course) which might prove to be another clue to thinking players.
Holes in the wall and splinters of wood are clues to the secret door.
Every room and every example has dressing that is directly related to a concrete fact in the environment. There is dressing that is unrelated to play, the traditional empty room option, such as the blind fish and crabs. These are red herrings.
Related to play
The mistake is when people use randomly generated dressing and dungeons and just communicate that to the players. The problem isn't in the random dressing, the problem is in the Dungeon Master just presenting that information and not attaching meaning behind it. That makes it truly just random, turning it into meaningless noise, which the players will then ignore.
But here's the awesome thing about random generation. It sparks the mind and opens a door into the chimerical reality of an otherwise empty space. You don't use random dressing tables to add in random dressing, you use random dressing tables to spark you to make connections about why that dressing is there. You can do this both in play and during prepreation.
This applies to the haunted house. If doors are slamming and shutters are clattering, there should be a reason. To scare your players, the reasons should be obvious and benign, until they are suddenly and horrifically not.
So if you've ever downloaded or generated a random dungeon that's filled with a random assortment of monsters and dressing and wondered why it didn't go well at the table, that's because the step that was left out was making sure most, if not all, of that random dressing remains meaningful.
here is a dead calm that is warm that smells like urine. The air is hazy with dust. You can hear sobbing and evil laughter in the distance. You find a pile of pottery shards and a cuboard here. You also see a scroll in the room.
Why does it smell like urine? If it's calm, why is their dust in the air? Who is sobbing? Who is laughing? What did the pottery jar do? What's on the scroll? This combination of random information should spark reasons that your players should be able to discover. Once they realize that there is a reason or purpose behind the descriptions and dressing you relate, they realize that those clues are the clues to their survival, making the game engaging and fun for them.
Hope this helps generate and inspire adventures for you, for a long time to come.