I sometimes visit friends who have really mediocre HT setups, but they mayplay something that just sound, at that stage so much better than my more "up market" system at home!
BUT, then I get home, play the same material and realize why I spend 4-5 times more than they have!
I am just amazed how a person can consider something to sound good at a specific moment only to realize later that your ears where fooling you!
Just in case anyone think that I am degrading less expensive systems, I am not. It is more a case of how your perception can change from one moment to the other.