Some double-standards are really asinine, but I don't find any inconsistancy in the cursing example. Since time immemorial, men have held themselves to a different standard than women when it comes to using foul language. I think some subs might find it comfortable to be held to a standard of cleaner language and greater purity.
Heck, you can make a case that master/slave relationships are BUILT on designing divergent standards of behaviour- at least in terms of consequences for infractions. Some of these standards make sense because of kink or comfort or historical context, and some don't and are just a sign of weakness and hypocrisy on the part of the dom.
(And just as a side note, having nothing to do with bambina's actual objection and having strictly to do with play, I sorta like the idea of using an inconsistancy in behaviour to make a sub feel like dirt. There's something sadistic about coming home late and saying to her "Yeah, I'm late. What the fuck are you going to do about it? That's right, nothing. Go get my fucking dinner ready." I wouldn't advise this unless she's turned on by sadism and verbal abuse, guys- or you might get a frying pan across the face.)
- FS