This is a pubic service announcement,
Wash yo' junk!
I have not had a real open sore yet, but occasionally I get some sensitive bumps where I tend to have the most friction. Once this clears out it will be a good idea to shower before the commute, not ride long durations with cotton underwear, or not ride with anything that may ride up, and do as jdgesus said. Try to isolate the cause - saddle/underwear/hygiene/butt position