Lee recognizes a joke from behind her when she hears it. She even scoffs a bit, alarmed but amused, before she fully processes that yes, that's a stranger talking to her. Or at least commenting on her drinking choices, which really all comes down to amounting to the same thing.

"Speaking from experience?" It sounds horribly dishonorable to cheat customers out of money, so she's not terribly concerned about how rude it is to mention when the barman's so close.