Poker is infowar. What you know of your opponent is your weapon against what he knows about you.
This information should be processed as raw data. For example: I watch an opponent play a low pocket pair aggressive preflop, follow with a continuation bet, then fold to a raise. I process this information as part of a pattern to be attributed to this particular player. The first time I watch this play out, I can't assume that next time he will follow a similar hand with a continuation bet, but I at least know that he is capable of it. If I do see this hand play out the same way, it reinforces the pattern.
The specifics of the hand can get in the way. In this scenario, there is little need to remember whether the pocket pair was 3 3 or 5 5; it was simply a pocket pair. When the information gained is tied to a hand in which you took part, specifics can get you in trouble.
If, for instance, you bet into a player while holding top pair and said player raises all-in on a draw and you call, the information gained from this exchange ends here. You learned that this particular opponent plays aggressive with draws and likes to semi-bluff. Whether the hand ends with your pair holding or his draw catching should not be part of the equation. If indeed this does turn into a bad beat, you may unintentionally taint the information. It is no longer data. It is personal information. It is emotional information.
To be better in poker you need to actively train your mind to remember odds, actions and tells. To be the best in poker you need to also train your mind to forget your feelings. There is no crying in poker, no sweet revenge. In the words of Michael Corleone, "this isn't personal, strictly business."