Haven't bought any 2nd hand games so far. Haven't sold any either.
I've been pretty wasteful with some of my 360games. E.g.

FM2 limited edition = Played like... 5 times only. Played online twice I think? Longest session, about 1 hour+

Saints Row = Played less than 10 times. Short sessions. Only 1 achievement unlocked.

Lost Planet = Played till the 5th or 6th mission only.

Dead Rising = Played once in a while in a period of 1 month. Still haven't killed that Carlito guy.


.......thanks to Gears Of War.