if you want to get the pulse of the crowd you need to go a few times. I would pay way more attention to the residents than the guests. The residents are there on a regular basis and will be looking to create a relationship with the crowd every week. A good resident will deliver a set that mostly caters to the core needs of the crowd while taking them on excursions into more experimental territory. A good resident will know how far he can push it before he needs to bring them back into “what they came for”. A good resident will build the trust of the crowd. The more the crowd trusts you, the further they will let you take them. so, check out what the residents are doing.
Guests don’t and can’t worry as much. They are not there on a regular basis and the crowd will expect (even if they don’t always like) a different style or vibe from a guest. As a DJ, If you have a distinct style you need to have some faith that the person booking you understands what you play and feels it will complement the line up that night. Don’t be the trance guy showing up to a drum and bass night.
The more underground Djs I have played with all have a passion for music and more importantly, new and exciting music. They want to take the crowd somewhere new. The sad fact is that many crowds can be quite conservative in their tastes. They want the “killer Saturday night” and not a lesson in music appreciation.
Treat your crowd like a 3 year old and your experimental tunes like vegetables. You want them to eat their vegetables but you can’t just put down a plate of cabbage and expect them to dive in and eat it up. You have to disguise ’em, cut ’em up, blend them with something they like and gradually up the quantity.