How often have you heard an upset controller? My office is right by the San Antonio Airport and I have a scanner on the tower freq all the time. Serveral times recently I have heard them get real short with pilots. There are a lot of trainee pilots flying into the airport in Cessnas and they usually end up on the other end of a comment like "why haven't you turned base yet?!?!?". Yesterday a Mexicana 737 apparently had a long slow rollout after landing and the tower keyed up and outright yelled " Mexico get off the runway!!!". It kind of makes things interesting.