i swim in a pool which is pretty quiet at lunchtimes so i'm lucky, plus my training partner works flexi so we adjust our times to the non peak bits. However i used to go to the local council pool which was laned, double width (ie 6 lane pool but was divided into 3 lanes, each being 2 lanes wide) so overtaking was no hassle at all. If i'm faster than people i'll overtake on the length as i don't see why they should have to stop at the end of a lane for me, i only do the tapping feet thing in coached sessions where we're all doing the same set.
Thing is i generally assume people don't mind if they get passed as long as you aren't holding them up. This isn't always the case though, once i was swimming with the mr, finished my set, waited for him to finish his, and he told me a guy had just been talking to him saying how rude i was for overtaking people in the lane. of course mr moose couldn't be bothered pointing out that he was with me. The guy at this point was swimming towards us, saw us talking, realised we were together and moved to a different lane (other half is a big lad). This same man had earlier asked me if i actually spoke english, i replied 'yes' and he swam off leaving me confused. If he had just said what his problem was then he would have saved his own embarrassment later.
I'm not rude swimmer, but i'm not going to say please and thank you each time i overtake someone, much as i don't expect people to do the same to me if they overtake, i won't cut people up, i won't squash them into a rope when i overtake, i just get on with my swim. The thing that annoys me is groups of people (usually girls) stood at the end of lanes having a chat. Obviously you need rest between sets, but it's as easy to squash into a corner so others can carry on swimming round you as it is to make yourself as large as possible and get in the way.