Working downtown you get used to seeing two main types of people - the homeless, and office workers. So far the office workers outnumber the other kind, but it seems to be shifting as time goes on... Generally you can tell which type someone is by the building pass they had strapped to their waist or worn around their neck.
Recently though a few post-secondary institutions, such as the University of Alberta, have opened locations downtown. Now we've got a load of younger scruffy types with no building passes. However are we going to tell them apart from the homeless?
I noticed something else - you can subtly tell the difference between types of people by what they have on themselves. If they are using or carrying a mobile phone they are probably not homeless. If they have headphones on, they are probably not homeless. A lot of student-types have mp3 players! Not many homeless people have them!
Finally, a way to tell the great unwashed apart from the homeless. Welcome back to school. :)