I think a gentle reminder that others are going out of their way to share titles should be proffered to any new-comers. I'll be devils advocate and like to think that some tend to get a little absent-minded with the excitement of having been given what they've requested, and forget to thank those who provided it to them. Obviously, if they don't acknowledge the fact or are more demanding than gracious, subsequently, then there's a bit of a problem. Politeness costs nothing, after all.
As for the fickleties surrounding things such as bitrate of files, unless specifically asking for a particular quality, (and even then, they should still express gratitude for having received anything in response), they should really show some kind of acceptance of that which is offered, even if it's not what they wanted.