Identifying small edges

[IgorSmiles]

The subject of whether to take gambles as a small favorite has been kicked around a lot. But how about if we take a step backwards first. I'm sure I'm not the only one to call off a nice chunk of my money with A/Q expecting a race, only to see my opponent turn over pocket Ks. Or to push with 9s, putting my opponent on two overs only to run into 10s or Jacks. Folding as a favorite isnt a formula for winning, we all agree there. But to state the obvious, you never really know the other guy's cards until he turns them over, so you may think you are taking a slightly better than 50/50 gamble only to learn otherwise. So, how are you identifying these small edges both preflop and on the flop?