Nosferatus, I think you're being a bit harsh here in your response, at least in the tone in which you wrote it.
I do understand the concerns if roleplaying becomes too distastefull and remains to be so. I've seen RP'ing where it seemed someone was just living out a rape fantasy or some sick !@#$ that had me disgusted years ago and also understand that the line for someone to be disgusted about something is different for everyone. This makes this discussion a bit difficult, as some find this RP to be over the top already, while others view this as acceptable and quite a realistic (not over the top) description of what is happening.
As said, the primary rule is that you can't RP someone else' char without their permission, but that is about the only solid rule that we've got.
Making solid guidelines on these matters would become impossible as everyone has different standards and if a compromise is reached you'll find those who think it's too harsh and those who think it's not harsh enough and both will be unhappy.
As a side-note, I do hope that when you ignore a character you also ignore their roleplays? So if you think someone is over the top for you, you can ignore him entirely?
