I guess that everywhere in the world you'll find someone who will always think he/she knows better and you have to listen to them.
I sometimes have problems of this sort. But I am not high ranking and am not training for a very long time so I guess people think they 'have the right to tell me how to do it'.
As for me, I always start by listening, even some of the most annoying of them, might have something good to say. If they wont stop telling me how to do something that my sensei thought differently and more logicaly, I tell them I learned it differently and want to do it as I know.
In seminars you see this more often, because people from all over the country come and each was thought by a different sensei. That is why I always listen first, maybe someone else knows better.
In the dojo it is a problem if such a think occers because you meet these people every class. I try to weave myself inbetween. I listen, I learn if it is useful and I ignore if it isn't and just continue the technique we're working on.
If someone would walk away from a partner because he thinks he knows better and the other guy doesn't listen to him, that is very bad aikido. In our dojo he'd have to face the sensei for such an act. It's rude, insulting and shows an overload of good for nothing ego.
enjoy training with other people, and as was said before, you can even learn from someone on his first class.