In general travelling to the US twice a year for the last 5 years I have found most TSA officers to be polite. Where I have an issue is when you have to place everything in the boxes to go through the scanner. Some of those working in that area are not so polite. It maybe the fact some people cause problems through not understanding what they have to do. This is not helped by those with larger carry on baggage than I have as checked in.
Its a gripe of mine that some people have too much carry on.