last time i arrived i wasn't asked for a return flight but when i told them i would be there for 60 days they stamped my passport for 30 (thanks, dick). to remedy this i had to go to the passport office and have it altered 14 days before returning to the US. while there, i was told it was not an issue to overstay your 90 days, you just needed to pay to get a special document to present upon departure. i was also told tha it's not uncommon to overstay your 90 days and extend it to at least 6 months.
i haven't tried any of this yet, but i get the vague feeling that they don't mind americans over-staying their welcome, but maybe they resent it when you try to hop to panama for a weekend and then head back for another 90 days or they don't like it when you don't pay to stay. i've heard about someone from germany being asked to leave after playing the border game 2-3 times, but never an american that i know of.
i haven't tried any of this yet, but i get the vague feeling that they don't mind americans over-staying their welcome, but maybe they resent it when you try to hop to panama for a weekend and then head back for another 90 days or they don't like it when you don't pay to stay. i've heard about someone from germany being asked to leave after playing the border game 2-3 times, but never an american that i know of.