Religions are fictional.
That would be something bad about herpes, or the girl.
Regardless of your views on religion, they do establish certain ethical rules. If a religion says oral sex is bad, then it's bad. This ties in to my original point that good and bad are human creations.
I'm sure he probably got a lot of oral at wal-mart, but I bet it wasn't bad oral.
I jest.
Oral might be good to one person but bad to another. Oral can also spread some diseases under the right circumstances. Yes, the diseases themselves are bad, but oral can transmit them, thus making it bad as well(from that perspective.)