Personal anecdote here, but I don't look like I belong in the loop for anything other than begging. I'm an overweight white male with long, typically unkempt hair, an untrimmed beard, and a pair of shoes that are dirty and have an obvious rip in the front. My jacket is dirty and often covered in mud / dust / etc. Most of the beggars I pass on my walk into work look far better off than I do.

I have never felt as though I couldn't get a cab in Chicago. Not during rush hour in the loop (when I could easily be passed for a well-off guy in a suit thirty paces down the line). Not at 3am when the bar is closing and there exists a line of upper middle class to upper class drunks failing over themselves for a cab. Not on Michigan at lunch. Endless opportunities to not pick up a ragged homeless guy, and money always plays.

Edit: Have a beard, unfortunately not an ursine.