Also in Identity Crisis at the gas pump...counting out change..
And in Publish or Perish where he is asked to pay 6 dollars for a bowl of chili and then the waiter amends the check because he forgot to add the 75 cents for the ice tea..(love that scene!)

But I get the feeling he wouldn't have it any other way. His social-status separation from his suspects is one of the things which allows him to get (if not keep) them off-guard. Make sense?

And his shoes in "Exercise in Fatality." When he and Janus are talking and Janus asks him if he wants a shoe lace. I think a complete new pair of shoes would be the call.