Waste of Money
If you take the time and spend the money to buy her a drink and she turns out to not even be interested, then it’s a total waste. Keep your money in your wallet and try talking to her instead of letting the booze do the conversing for you. Any potential girlfriend wants to have an actual dialogue, not to stare at you across the bar while you treat her to a fruity drink. If she isn’t interested at all, then you get to watch your hard-earned money go down the drain while she enjoys the drink you paid for and got nothing out of it. To add insult to injury, she’ll probably laugh with her friends about how much of a sap you were to buy her a drink.
Depending on how confident and easily offended the woman you’re trying to flirt with is, what you think is generous may come off as horribly presumptuous. Sending a drink her way sends a message immediately. It tells her that you want her, and that you’re only interested in talking to her because you want to hook up. A lot of women won’t stand that, and the angrier ones may just send the drink back at you – possibly without the glass. If she isn’t interested and there’s no buildup, she’ll think you’re just being sleazy and she won’t be happy about it.
What to Do Instead
Rather than forcing a drink on her without even giving her any options, spend some time talking to her. After you two talk for a bit, offer to buy her a drink when you buy your next one. That makes it seem less like you’re trying to butter her up and more like you’re just trying to be polite and not drink in front of her when she doesn’t have a drink. She’s much more likely to agree this way, and you’ll get to send the message without being too forward. Another perk to waiting is that you can let her pick her own drink. If you buy a drink for her, you might end up getting something that she hates and she’ll be angry. If you buy her the same drink that she’s already drinking, then you seem uncreative and she won’t be interested in that either.