Antonovman - I agree with you about LUX
Roho - I have also had some awful times at MIA including having to stand around outside the aircraft in the rain for 2 hours whilst Customs pulled it apart...and we'd only done a domestic ferry flight.
But for me RUH is the worst - handling agent totally disinterested and rude, usually 2-3 hours in Immigration for no particular reason, and at the end of the day you can't even get a beer.It's cr@p.