(prompted by discussion of porn use at GoGaRuCo - see here, here)
Quick thought: It's not that the community needs to ensure offensive content never happens, or that the community needs to find a single standard of what is appropriate.
The key is the right to complain safely. When complaints are predictably met with accusations of "overreacting", "political correctness", and "intolerance", the resulting message is: Be like us, be silent, or leave.
If you reject the criticism, then try something like, "I think you're wrong, but I accept your right to complain." Complaint is feedback, it's a legitimate part of a community's communication.
(Let me clarify that I've had mostly really good experiences in the software communities I participate in!)