In my last blues band the guitarist starting wearing a hat that gave him that SRV look, so I can forgive him that as he did look cool (and had the 'LICKS' to back it up).
Baseball caps I can't abide! Worked with a guy once who I never saw take off his baseball cap, day, night, restaurant, on a plane. On one occasion we were waiting for transport in an army canteen, he still wearing said cap as we eat, an army guy walks in, I can see the immediate rage in eyes, walks over, takes the cap and puts it straight in a bin. Brilliant. Should be made a standard policy.