I rarely encounter this problem, and if I do I ask them to refill it and watch for when I'm ready for another refill. Then again I'm not a prodigious drinker(minus water or alcohol) so usually a refill or two will do me. What I hate is the smug attitude that servers should be sucking your cock continuously and make sure it doesn't drop below the 1/2 way mark. Who the fvck cares? I've never waited tables, nor do I think people who do are special, but I sure as hell am not that goddamn anal-retentive over a fvcking drink!
I've found that because I tip well(20% ~) that I'm always recognized, given great service, and generally never have an issue. I don't want this to come off as snobby, but I've noticed a general increase in service the better I'm dressed. I typically go out to eat in nice jeans and a dress shirt at minimum, and I haven't done the t-shirt+shorts in a LONG time. At minimum I'll do a polo and shorts albeit rare. I've just noticed that if you are younger you have to dress nice to get the BEST service. The better I dress the better service I get from any service job, as well as how polite you are. For some odd reason some people think they can leave their trailer, put on a pair of cutoffs and a Winston t-shirt, get in their 82 Beretta, and then go treat a server like sh!t. If you do that I promise you will never get great service, and idiots like that NEVER tip anyway. Call it shallow all you want, but even if you are dressed down you don't have to act/look like a bum.