I saw these people all the time when I was in college. I very quickly learned that if I saw a pair of well-dressed young people walking around campus, I should avoid them.
Usually they'd accept a polite "no, I'm not interested" but some of them could get quite pushy. I once had to give a fake phone number - I wish I'd known about those "rejection" numbers you can give to guys at bars when you don't want to see them again.
Haven't been bothered recently, though.
These people believe it is their job to go around talking to people and trying to save their souls. I don't have a problem with that. I
do have a problem when they won't take no for an answer.