If you expect to always find the best move in a chess game, you're holding yourself to an impossibly high standard. Even world champions make lots of mistakes.
But it's not unreasonable to expect yourself to always LOOK for the best move...even if you don't play it.
With that in mind, here's a little experiment. I'll show you last night's game without notes, and you (without use of the computer, please) try to figure out why I was mad at myself.
Some folks on Facebook already know the answer. No hints, please!
P.S. Monday 8/4/14: maybe I was a bit too hard on myself, as some strong players also missed the combination. Here's the critical position: