I've allowed myself to be dragged into a tedious and pointless argument over what constitutes a good or a bad bet. The person arguing with me is either dumb as a box of friggin' rocks--which I don't believe--or he's just pursuing a personal vendetta, because I dispute many of his political claims. The pointless argument obscures the question, which is important enough to reiterate the answer to.
Whenever you gamble, whoever you make a bet, you (presumably) don't know the outcome. The decision to bet or not bet should be based on expected value. A bet with positive EV is a good bet. A bet with negative EV is a bad bet.
Note that this is exclusive of the eventual result, because logically, one cannot factor the result into the decision. It isn't known when you make that decision.
You see this in all sorts of situations. The worst thing you can do is tell yourself that a bad bet was a good one because you happened to win. Equally bad is telling yourself that you made a bad bet because you happened to lose.
Think rationally and logically!