You see it all the time in online play, particularly in tourneys. Someone wins the pot with a stone cold bluff, then shows their hand to let everyone know they won with a stone cold bluff.
It's tough to blame then. It's a rush to win with a stone cold bluff, and you want people to know that you schooled them. But it's a bad idea. Because people who need to show that they won with a stone cold bluff fall in love with the stone cold bluff, and when you fall in love with the stone cold bluff, you've fallen in love with danger. Because sooner or later you will get called, and you will be gone.
It's the same thing with small pocket pairs. People fall in love with pocket pairs of any sort, but for some reason known only to God and themselves, they bet heavy on small pocket pairs and, almost inevitably, lose. It's probably cause they won big with pocket 4s once, or pocket 2s. I understand that. I won a huge hand once with Q-7 Diamonds, and I always play it now if it doesn't cost too much to do so. But I shy away from small pocket pairs. Oh, I'll call the blinds to play pocket 7s and under, but I don't raise the big blind unless the pocket pair is at least 8s. (On the other hand, I just went all in and won with pocket 9s. And on the next hand eventually called an all in with pocket 10s and lost. Oh well.)
I guess what I'm getting at is: The toughest decision you make in a hand is almost always your first decision. Some of those first decisions are easy - a 7-2 offsuit, for instance. Pocket As. sitting in the big blind with crap but it comes around to you and no one has done anything but call. But most of them aren't. They depend on so many factors. Your chipstack. Your position. The table image of the other players. What's happened in front of you. All these things come into play. At least they do for smart players.
As Mike Sexton says, the key to poker is making good decisions. Now making good decisions doesn't mean you'll always win. But remember (switching games for an instant), hitters hit home runs all the time off good pitches. A home run doesn't necessarily mean the pitcher threw a bad pitch. But you have a better chance of winning if your pitcher is throwing good pitches, just as you have a better chance of winning at poker if you are making good decisions.