The craziest one I saw was an immogration officer at LA who tore into a Swedish diplomat travelling on a Diplomatic Passport, demanding to know exactly what he was going to be doing in the US or he wasn't going to let him in! The guy was on the staff of the Swedish Embassy in Washington.
We have had some very pleasant US officials on our trips to the US but they have been outnumbered by the rude or non-communicative ones. LA is escpecially bad.