It varies really with what you can do. If you're just on a date then you kinda have to really pick your battles but be smart about it. You're almost powerless. You're a stupid fvck for taking an attractive girl to a bar that you aren't in a solid relationship though, so the only person you have to blame is yourself. If the girl suggests going to a bar on a first date or two then you know you have a lush on your hands. Like I said, it's happened to me while I've been on dates AND when I was in a relationship and it's not just bars that this can happen. I went out with this girl once to a restaurant and wouldn't you know it, we had a guy waiter that was flirty from the get-go. He was so f'ing pathetic, he wouldn't even look at me when taking our order and when he would come to refill our drinks he'd refill hers and "forget" mine, followed by some line "oh, sorry buddy, my bad, didn't mean to leave you out like that". I'm thinking "this fvcking guy" but I don't say nothing to the girl. I got my revenge at the end when it came tip time. I made sure to put a big @$$ 0 with a line through it and the girl asked "did you leave a tip?" and I said "yep, sure did". I just wish I could have stuck around to see the reaction on that douche's face. Again, it was just a date and I was helpless in what I could do BUT I picked my battles and fvcked him over in the end. I hope he was depending on my tip to pay his rent and now lives in a box on the corner of the road.
Another time I was at a local bar with my girlfriend of 6 months, well established relationship. We'd been out to bars before but never had any random dude's approach us. We are sitting there talking and laughing and all of a sudden this random dude comes and sits down and says "how you guys doing tonight? How you doing pretty lady, I'm Mike". I literally laughed out loud and said "dude, are you fvcking serious? We don't give a sh!t what your name is." Then he said "oh sorry bro, my bad, I didn't know ya'll were together". I said well now you know so fvck off, we ain't here to make friends. I said it in a tone that he understood. He knew if he got all butthurt and wanted to fight that I'd likely break a bottle over his head and shove the jagged end up his @$$. My girlfriend thought I handled it brilliantly and I got some wild sex that night.