I'm often amazed at how kind and polite the people staffing security screening sites at airports outside the US are. Granted, there are many kind TSA agents (especially at the airports where I usually begin my journeys -- Greenville/Spartanburg (SC), Lexington (KY), Cincinnati), but I have encountered a lot of hostile TSA agents and airport employees at major US airports. The worst spot for this from my experience is going from the international side of an airport to the domestic side on return to the US and the required negotiation of immigration and security. On my last return, an airport employee screamed repeatedly at someone because she asked a question about which line to get into when it was no at all clear which line to get into. An authoritative, stern, loud voice aimed at all who approach the security containers seems to be the default at security, and scolding of anyone who doesn't understand the security rules is common. I have seen quite a bit of unkind, inappropriate, abusive, unprofessional behavior from TSA agents -- particularly at Atlanta. TSA culture there is horrible.