So, you're a lonely single guy, and you see a group of two or three women sitting in a booth at the bar. You want to go over, buy them drinks, sit with them. What's your best means of approach?
Well, sorry to tell you this, but we women know that the only reason you're doing this is because we're women and you're a guy. There's really no reason for you to pretend otherwise. Try to be ... nice. A little bit flattery, a little bit of look of appreciation in your eye. Nothing gross, nothing over the top. Be pleasant. Just a "Hey, you're some very attractive women. I'd like to buy you a drink." Even, if you must, "I'd like to get to know you."
This will save untold time and annoyance on everyone's part. If you're reasonably good-looking, or having any selling points at all, it gives any women in the group who might be in the market a chance to send you "potentially interested" cues. And it cuts to the chase for the completely not interested. We can say, "Gee, that's sweet, but: boyfriend. Husband. Talking about stuff. Not a good time."
Sub-category tip: this won't help you if you're in town for one night and want to get laid, but if you can afford it, and you're coming back to this bar again, it never hurts to say something polite ("Those are lucky guys!") and offer to buy the drinks anyway, no strings attached. If you do this, you have to mean it: NO STRINGS ATTACHED. It does happen, that guys buy you the drinks, they bid you adieu, and disappear into the bar. This, friends, is an investment on building good will, and everybody needs goodwill. You don't want to be chatting up a girl months later and have someone in the bathroom tell her, "Yeah, that guy's not bad looking, but he's an asshole."
Similarly, your WORST strategy is to try to buy women drinks and sit with them, all the while disclaiming how you're not hitting on them and you're not trying to pick them up. You are, and you are, and it just makes you passive-aggressive. That's not highlighting your best quality. Guys with this approach seem to think that if they bully you into letting them sit in your booth, then they're in, which is, frankly, delusional. And far too often, they turn into jackasses when you don't flirt with them. We're not there to flirt with you, and if you'd followed my belated advice, that would have been clear from the start, freeing you to try your luck elsewhere.
Think logically, for a second, through the beer and the hormones: your whole approach was based on the fact that you weren't interested. The target audience is women who are cool with your not being interested in them, because they're not interested in you. These are the ground rules that were established in the beginning. Then you get mad because you're not getting anywhere.
I imagine this approach must have worked for some of these guys at some point, but it almost seems guaranteed to lead to encounters where somebody is going to be pissed off the next day.
At any rate, the guy who tried the losing strategy last night at the dive bar did make up for the annoyance in amusement value, because he told me I was "laid back" and reminded him of his sister. He went on to drunkenly tell me that she's a Lutheran Sunday school teacher with eight kids. Now, if that isn't me, I don't know what is!