A friend who is ethnic Arab and muslim,but born and brought up in USA,and an American Citizen,overheard this conversation between imigration officials when he went back to USA after visiting his extended family abroad.
It goes like this...approximately.

"He looks Arab"

"Yes,i see"

"He is a bit arrogant,and i suspect he is up to no good"

"Well,did you run a back ground check on him"?

"The results are sketchy"

"Are you saying he was involved in a crime at some point"?

"No,he has been in and out of the country many times,and has been visiting Arab contries".

"Are you suggesting an arrest?".

"Probably...under Patriot Act,he looks suspicious".

"He is arab,isn't he?"
"hahahahahahaha.......yes".

"We have booked too many this week"

"oh..he is lucky".

"you can flag him...if you want".

"May be next time".

Ok sir you are free to go.Here is your passport.

The above mentioned friend now lives in Britain,for good.