Looking at the clothing at a rave, you see a group of people whose concerns are more about being comfortable than if they can bring someone home for the night. The closest thing I can think of to the atmosphere at a rave is the one at a child's birthday party. Nobody thinks to care who they are impressing with the way they look. If you want to dance, you can. You don't need someone to dance with.
People are there to have a good time.
This is where the drugs come into play. The reputation ravers have for being chronic drug users seems well founded at first. Kids stay up all night dancing. Everywhere you look there are kids drinking water and chewing on pacifiers, and giving back rubs. These things are always portrayed as a side effect to the drug use in the media.