Yes I do.
And I don't do the usual trendy thing of recognising I've stereotyped, feel guilty and then consciously act against it.
I just reserve judgement usually til the situation has passed.
Eg if there are some aggressive, swearing black youths ahead, I'm going to stereotype them as scum and will do so til they apologise for being in the way/get out of the way without comment or hassle. After that I'll say "that stereotype was unfair but it kept me alert".
Or more likely.
"bloody swine"

;p