I appreciate when customers come into the bar and want to buy drinks for other customers. It's a nice gesture. It's thoughtful. It also increases my sales, which helps to increase my tip amount at the end of the night.
What I find really annoying is when I am taking an order from a customer, in particular a male customer, and they spot a female whom they find attractive standing at the bar (usually all the way at the other end of the bar from where the customer is placing his order with me). After he places his order with me, he then tells me..."And I want to buy whatever she is drinking." as he points to the woman standing all the way at the opposite side of the bar. This is when I grit my teeth and pose a fake smile. I have to keep my cool and not let these little things get to me. I now realize that this whole order transaction is going to take a lot longer than I originally anticipated. Plus, it screws up my order taking flow. Now I have to walk all the way to the other side of the bar, ask the woman what she wants, explain to her that the nice guy at the other end of the bar wants to buy her a drink, make her the drink and then close up the rest of the transaction with the well intentioned male customer. His sorry attempt at landing some ass at the bar ends up costing me more tip making and order taking time than it's worth. Plus, most of the time the pretty woman at the end of the bar isn't alone. All her friends are standing right behind her. So when I go to ask her what she is drinking, she then takes that as a green light to place her order with me for her and all of her friends.
Oh man. The chaos that ensues.
So please guys (Yes, I am addressing the guys directly on this one because I have yet to have a woman customer do this to me), if you are going to buy someone else a drink, ask them themselves what they would like and then deliver the drink to them directly. Don't make your bartender the middleman/middlewoman. Besides, going up to a woman directly and asking her what she would like to drink and letting her know that you want to buy her a drink is a surefire way to get a conversation going. That is what you are seeking, isn't it? It also shows confidence (which women love) and you will be saving your bartender a whole lot of unnecessary legwork.