I think Paul should have told the police about his roommates' date rape drugs instead of pulling a sitcom switcheroo. Think about it, they'll just go out and buy more and keep doing it.
I've listened to enough Geto Boys to know what happens to snitches, but I think some crimes are bad enough to warrant it.
Umm...I've seen this movie a bunch of times and I don't remember the roommates getting caught with the drugs. After the fight, we don't even see them again until the "American Graffiti"-style ending.
*SPOILERS*
One guy got set up by a shady corporation and went to jail, another guy messed up his brain trying to create a new drug, and the other guy...went bald. I think that's my main problem with their fate. Going bald is not nearly enough of a karmic punishment for date rape. Baldness happens to a ton of men all the time and they just find a way to deal with it one way or another. The guy came from a rich family, he could probably just beg his dad for hair plugs or whatever.
"Don't let those empty people try and interfere with your mind"--Black Sabbath, "Under The Sun"