*puts psychology hat on* you do realise we're hardwired to judge, stereotype, and make snap decisions about people based on trivial things like how they look and dress? Its only very recently people have been pushed (this is especially true for dating) to get to know someone and NOT judge so much.

That being said, you're dealing with young people mostly, right? I used to tutor at uni back in the dark ages, I've seen the same thing. The difference in motivation between mature age students and youngsters can be dramatic. Some of them you swear they don't want to be there and don't care. They don't. They're too immature to realise they're onto a good thing and a good qualification can set them up for life, they're just there cos some school counsellor or their mum said they should be here. Some people never grow out of that stage and never do anything good with their lives. Some people just need some time. Some respond well to external motivation, some eventually get a spark from within, some ignore everything completely. I've met people in their late 30s who are complete 'losers' because they can't/won't seize perfectly good opportunities that people go out of their way to give them and are happy to play victim.

I'd try and step back and not get personally involved, its their lives and their decisions and people are hard to change, even some youngsters. Just be the best *you* can be and if it lights someone else's life up that's great, and if they don't like you or you don't like them that's fine too.