I feel it may be worthwhile to note down my First Thoughts and Second Thoughts- with apologies to Terry Pratchett -on this
First Thoughts: "but if you call yourself a lesbian and sleep with men, straight guys will think we can all be Persuaded!"
Second Thoughts: "the kind of guys who would keep going even after hearing 'no thanks, I'm a lesbian,' already think that way. and do you really want the onus of preventing men from being assholes placed on queer women's harmless behavior? no!"
remember that it can be normal to have a knee-jerk mental "WTF" reaction to apparently contradicting identity labels; you can't really control that if it pops into your mind. but you should often try examining it further
and at the end of the day, you don't have to Get It to keep your mouth shut and be respectful