Tough to be unbiased here – I walk through that neighborhood every day during my commute, and feel that a description like that is hardly a useful constraint. Especially in the few blocks around the art school (which leads toward two other undergraduate colleges), you can't tell which folks are professors, which are students, and which are leeching off the zillion hospitals within three blocks.

To some, that may mean it seems appropriate to just stop and question everyone. But, in reality, being questioned by the police appears to passers-by to be an indication of guilt, and that's not something you want colleagues and students seeing.

So, again, if you see a guy matching a vague description, see if there's another reason why you'd suspect him.

Have a rock-solid, specific description? Maybe that's a different story. But I'd like to err on the side of caution and respect – there are consequences even if you don't charge the guy.