I had an experience with switching seats a few years ago. I was flying FRA-DTW and had a window seat. The person in the seat next to me asks if I mind switching with his daughter so they could sit together (she was a teenager a few rows back in an aisle seat). I like window seats and with a relatively long flight, I really didn't want to give up the seat. We got delayed on the tarmac for about an hour and during the delay, the person next to me pulls out a meatball sandwich and a 2-liter bottle of a clear liquid that suspiciously smelled like vodka. He gets his sandwich crumbs all over me and starts taking swigs of the vodka... I quickly changed my mind and switched with his daughter before take off. I was pretty upset at losing the seat, but later found out that IFE wasn't working in that seat. So I guess it worked out in the end.