Well, duh, they show off your bad taste, but blisters happen, as do communal showers. If you can avoid racing 10ks in racing flats that leave their mark, avoid flip-flops. Case in point, I raced a 10k in spikes last weekend and had a nasty blister on my heel. I wasn't interested in irritating my abrasion further, so I wore my shower flops about campus. If you must wear flip-flops, go cheap, as you shouldn't have to wear them that often.