I can tell you from first hand knowledge that one of the bars here in Madison was caught on camera denying a black man with a white group of friends entry into a bar for breaking dress code while the white members of the group with the same infraction we're allowed in. The black guy rightfully brought this to a lawyer and the bar offered a settlement within 48 hours of the demand letter.

While not all bars discriminate with the dress code, some do in fact use it to do so. If you want to make quick cash and your black, go out with a white group of friends breaking some minor part of the dress code and film the attempt. If they deny you but not them, see a lawyer and send a demand letter, claim a few thousand dollars by the end of the next week.