Man I just mentioned this on the 'Caught Red Handed' Thread on this page a few minutes ago.
I go through IAH customs all the time, most usually now from Belize and Brasil, and sometime Europe.
They are fast and 'great' in my book. I get in with Liquor, Fruit, Conchs, etc
it is the 8th largest customs and entry point in the US so they are busy, but who knows........
I just cleared BWI customs the other day coming back from Oman on a tail swap (the AF normally brings it's planes through BWI) and they were a bit more strict.
The only search I had was in Miami, where they thought it odd I was bringing back license plates (I collect them)