Be careful when evaluating others and their actions that you know all the facts before making assumptions. If you don't it will only make you look silly later. Sometimes we perceive a situation a certain way and assume an outcome which is not true. We then build theories, ideas, and opinions based on those assumptions. The problem comes when those ideas are incorrect. Suddenly everything we've built up is wrong because its been built on the wrong foundation. Unfortunately this makes us look stupid. I'm notorious for doing this when talking with my wife. I will finish sentences, assume the outcome of a conversation and just generally make the wrong conclusions because rather than listening (or asking and then listening) I jump to my own conclusions. Invariably I look dumb.
If you find yourself questioning something which looks out of character for someone-be direct and ask them privately for more information. Rather than making assumptions, building a complex theory on that assumption and then running the risk of being completely wrong later; just ask. This does require a bit of humility and that can be difficult for some. In the end though you'll save face and you won't be left looking like the fool.