I'd say that the situation would have to be pretty rare in which I would sing dirty lyrics. Suggestive is one thing but out and out dirty is another.

At our monthy shanty sings at the Hyde Street Pier in San Francisco the last session of the evening is reserved for adult lyrics. Usually this ends up being songs, rarely shanties, more recently written for effect. I have, very rarely, sung dirty lyrics in this setting and found myself feeling very embarrassed.