Since I don't drink, I always think its really funny when people ask me if I mind if they have a drink whilst in my company... because what I really want is for people to ask if I mind if they fuck someone else.
I'm not sure in either case if I said if I minded that they'd refrain, but I'd definitely rather spend time with a tipsy person than someone who has a hard time respecting emotional and sexual boundaries.
While we all stumble sometimes, I like people who can mostly walk their talk. Ask me, don't tell me. Be willing to hear, respect, and even act on my answers. I like to talk, and I like people (including me!) to be happy; we can work it out.
I don't care if you have a drink. If you get wasted, I may leave. But I appreciate the conscientiousness expressed when you ask me. It's a good sign.