One of the problems singers have is that they're scared of people breathing cold'n'flu germs over them, and alot of the time they're stand-offish it's because they're just trying to keep out of harm's way, especially if they're on tour and have a load more shows to get through. I'm not making excuses for rudeness but I know many singers worry about this.
As for the "don't you know who I am?" comment - the best response I ever heard to this was the receptionist putting out a message over the tannoy saying "There's a lady here who can't remember who she is. Can somebody please come and claim her as she's holding up the queue"
Isn't that weird. It wasn't me who posted about Gene Pitney!