Have you ever been detained at immigration/deported? Why? Was it an unpleasant experience?

Last time I went to New York, I wasn't allowed in. I had my passport taken off me and sent into a waiting room for 45 minutes. When I asked an official (black uniform, gun, limited grasp of English, scary) why I had been stopped, I was shouted at that there was a queue and I should sit down and shut up. Eventually some airline officials came in. They asked why I was stopped, they said they didn't know, and said that this wasn't an uncommon occurrence. After some more waiting I was given my passport back and allowed through customs. They never explained that the hold up had been, and I was given no apology. Overall, 6/10, it could have been a lot worse, but it was still very intimidating and not pleasant at all.