People notice, but only to a small degree. When I was out in SF back in July I didn't intend to drink much at the meetup. I think I had 4 drinks total, all were bought by someone else for me. If I had declined the drinks, or gotten something non-alcoholic instead, I doubt anyone would have made a fuss about it.

Well.. and PJ did shove like $15 in the jukebox and demand I pick songs, and gave us money for the taxi ride home which also paid for a nice pizza back at the hotel.

I don't think the problem is other people noticing as much as thinking they're noticing. You can feel a bit weird if someone goes "beers for everyone?", everyone's agreeing and you're the one that has to go "no thanks, a coke would be nice". Or worse, just order it and put it in front of you. People do tend to assume everyone drinks beer.

(For me, that's not true. I don't mind alcohol, but I can't stand the taste of beer. I can't finish a zip of it, let alone a glass. I do sometimes have to explain that. Since I'm old enough to have a driver's license I sometimes have the nice excuse that I still need to drive. Works a bit better in that it requires less explanation.)

It's possibly because I just got out of college, but it really bothers people when you don't drink. A lot. I didn't drink the entire way through, and I got a lot of comments later on. People weren't very forward about it, but after some prodding, they stopped inviting me out because they felt that I was judging them by not drinking, and therefore I was a buzzkill. I didn't draw any attention to it at all, I had a Coke in my hand the entire night, but it still made people upset.

People are silly.