He could have come back with any number of insults. Several of them danced to the tip of his tongue, but he didn't voice any of it. Instead, he leaned forward and kissed her. Either it would be the right thing to do, or the wrong thing. Crowley was prepared for either scenario, because Anna could go either way. That was part of the fun, for him, trying to second guess how she would react. She kept him on his toes at least, and he appreciated that.