Wan Chai can be pretty grim for many, it's full of dodgy looking girlie bars that are a very thin disguise for hookers, frequented more often than not by pretty grotesque over-weight drunk and lary old men - who really should show a bit of discretion about paying for sex from people probably economically forced into it.
There are of course other sides to Wan Chai, but this is the most immediately obvious.
I've had fun there with big groups out to take advantage of happy hour cheap drink offers and dance in some trashy 'Coyote Ugly' style bar, but generally speaking it's not a place I used to head to for a 'quality' night out. Although just to reiterate, I have been to a few nice places there.