After 3 (2 done with local anaethetic, one with a general) surgeries for a saddle sore gone horribly wrong, I will NEVER again wear a pair of shorts for more than one day. Probably my reaction is a bit extreme, but my 'pain in the ass' kept me off of a regular bike for about 4 years.

To me, it's just safer washing my shorts every day, or failing that, carrying 3 or 4 pairs. They weigh next to nothing and compress prety well, so I'm not going to risk infection again.