It may come as no big surprise, but in an admittedly unscientific poll of over 1000 Airfarewatchdog.com visitors has determined that the old school "legacy" airlines (American, Delta, United and US Airways) have the rudest personnel.
Newer and smaller "boutique" airlines such as Virgin America and JetBlue, in contrast, came in "last" on the employee rudeness scale, an honor they share with other smaller airlines such as Alaska and Frontier.
I say "no surprise" because the newer airlines come out on top in survey after survey of customer satisfaction, such as the 2012 J.D. Power airline rankings and the most recent Conde Nast Traveler Reader's Choice Awards.
In our survey, American Airlines (perhaps owing to their recent labor strife and bankruptcy filing), led the poll with 25% of respondents voting its staff "rudest," while only 2% chose Alaska, Frontier, JetBlue and Virgin America for this dubious distinction. Next "rudest" was United (21%), followed by Delta (18%) and US Airways (12%).
Personally, I rarely find airline staff to be rude, and I mostly fly the larger legacy carriers. If you treat crews with kindness and respect -- a simple hello and good morning upon entering the aircraft, leaving the tank tops and gym shorts at home, that sort of thing -- they usually respond.