Under normal circumstances Sam was a flirt too, and it was easy to go through the motions, to summon up a particular kind of look and a particular kind of smile. Sometimes he didn't even realise he was doing it, really, just another way he'd been changing how he presented himself to suit the environment his whole life. Code-switching body language.
The first few seconds through the door he was too surprised they'd actually gotten what they were looking for to realise what Harley was doing. The knife in the hand was a little hard to ignore, though, and he had a bit of an internal groan to himself - oh Jesus fucking Christ, it's like THAT - before he noticed the rest of the room start to react. Well. Looked like he didn't have to figure out what side he was on just yet, because everyone else pretty clearly clocked him as being with her. He could have been an innocent bystander who just happened to be walking in at the same time, it was kind of plausible, but noooo.
Whatever. He smoothly side-stepped the first guy coming at him, grabbing the nearest bottle of-- cola syrup? - from over the top of the bar so he'd have some kind of weapon. Redwing screeched angrily somewhere above him.