My friend i have a crush on, has a crush on a druggie...best course of action?

she thinks it was "love at first sight" because coincidentally they made eye contact. she has never met him and he has never met her. so she likes him based on looks and has no idea what he is like. I really do not want her going out with this guy because he is on probation, has been in multiple fights, caught for drugs in middle school, and hangs out with the goth/life hating group. I can't really tell her these myself because every guy she has told me she likes, ive pointed out there problems. so she might not believe me and think im just jealous. I really do not want to see her end up like him....