The line between 'tasteful' and 'offensive' is a very fine one, and one that shifts a lot. The only line we have in the rules re: offensive is the stuff banning personal attacks, and it's for a reason.
To some people, the non-con section is offensive.
To some people, the vanilla section is boring and not what they want to read.
To some people, the exotic sections are just not right.
To some people, the bondage section is just totally not their thing.
Do I even need to mention the extreme section?
In that light, if someone puts together a username that says "URMOMFCKSGOATS", then it would be against the rules and we would ask them to change it. But considering the variety of people we have here, it seems awfully close-minded to look down on something not because it's against the rules, but because it 'isn't decent' or something similar.