The races I do are cat 3 crits, and unless you are part of a team, then it really doesn't matter. I can do a race this Sunday and wear my Liquigas kit and win, and nobody will bat an eyelid. But I don't, and I wear my my club colours since I'm a member of them and therefore feel I should wear them when I race no matter what. To me I'm representing and promoting my club, and when I do any long rides/sportives etc., I always wear them.
I have never heard of a case of somebody having their licence pulled. I mean guys have DQ'd for moving off their line in a sprint or riding on the back of a higher grade they are not in, they also get DQ'd.
A mate of mine wears the colours of the bank that he works for, but then he has sponsored races for the two clubs on the GC, so I guess that is OK (and FTR he has won more then me).