Bad choices aren't as common as a person might think. Choices are often made on the basis of what seems best at the time. Only later, when the results fail to meet expectations, does a person look back and say, "Wow, that was a bad choice." What they really mean is they don't like the way events unfolded afterwards.
Any decision is rooted in three domains: emotion, knowledge, and wisdom. Each plays an important part in making a choice, and in certain situations each can take the dominant role. As is often the case, it is rare for any three voices to be in agreement, so for any choice that is made, there will always be the "should have, could have, would have" lurking in the back of the mind, waiting to present itself with "see, I told you so - if only you had listened...". Life being what it is, almost every decision has a down side to it, so there is always something to regret. A person who dwells on how choices might have been made differently will not find much but frustration. Most decisions have an upside, so the optimist will recognize that something good comes of each choice, and accepts that negatives come as well. Rather than seeking to change the past, the positive approach is to learn from the experience, and apply it towards future decisions.
Emotion is a powerful motivator. It is the only factor in decisions made as small children, and remains powerful throughout adulthood. Need, desire, hunger, thirst, discomfort, warmth, love, hate...all such stimuli drive an emotional decision. Emotion only considers the present. "Right now" is the hallmark of emotional decisions. (For most people, "should I have ketchup or barbecue sauce?" is an emotional decision.)
Knowledge is acquired over time, through study and experience. It works to temper emotion, providing known facts and consequences for potential decisions. Knowledge has its limits in what is known. If a person has no knowledge (or incomplete knowledge) of a situation, a rational decision is unlikely. Knowledge tends to be dominant in making decisions when there is time to research or analyze the choices to be made. ("How should I invest my retirement funds?")
Wisdom too is gained over time, and much more slowly than knowledge. Whereas knowledge deals with specifics, wisdom heralds a broader understanding of life and people in general. Wisdom provides guidance when facing unfamiliar decisions. Wisdom also can serve as a tie-breaker or compromiser between the other two. Choices made with true wisdom are those least likely to be considered "bad" later on. The trouble is that there is no real test for wisdom. (For that matter, a part of wisdom is recognizing "I am fallible", and embracing what is unchangeable.) Empathy, too, is a part of wisdom, as the ability to understand without knowing can shape decisions that involve others.
Consider the following scenario:
A business man in his thirties, married to a woman he loves greatly, is sent to a two-week conference in another state. During a social interlude, he makes the acquaintance of an attractive woman who works in his field, and they hit it off well enough that they spend much of their free time in one another's company. One evening, she invites him back to her room, without any pretense as to what she desires. He is faced with a choice. From an emotional perspective, he'd really like to go with her. He does find her attractive, he loves his wife, and it's been a week or so since he's been with a woman. The knowledge he has available includes several facts: he is married, he isn't likely to get caught, his wife would not be happy if he did somehow get caught, and this opportunity is not likely to present itself again. Wisdom suggests to him he would carry the guilt of having betrayed his wife's trust if he does go with the woman. Depending on the force of these factors in this individual, he makes a choice.
Choice #1: He goes with the woman to her room. (Presumably they have a wonderful time.)
Choice #2: He regretfully refuses the woman's offer. (He then goes and calls his wife for company.)
With the information you had, and your own personal views, you probably have an opinion as to which choice he should have made. But consider the two possible aftermaths, and see which choice the man would view as "good" or "bad" when he looks back.
Aftermath A: The man returns home to his wife, and they live full and happy lives together.
Aftermath B: The man returns home, only to discover soon after that his wife secretly loves another, and she wants a divorce.
The future is always unknown, so it is difficult to predict which decisions will have the outcome we desire. If the man made Choice #1 and Aftermath A came about, he would likely look back on his choice with guilt, and consider it a dark point in his past - a bad choice. Had Aftermath B occurred however, he would likely view it as a good decision, particularly if it led to a fresh and longer-lasting relationship. If he went with Choice #2, the reverse is true. Aftermath A makes it a good choice, with only perhaps a lingering "I wonder what would have happened..." to entertain him at dull moments. Aftermath B would leave him kicking himself for eternity, as he didn't take advantage of what he had, and wound up with nothing (or less than nothing, depending how the divorce went).
In the end, people must make the best decisions that they are able, afterwards dealing with whatever consequences may come. The important thing is that "bad" choices are recognized and not repeated in the future. There's a famous quote: "Those that refuse to learn from the past are doomed to repeat it" ...and deserve to be kicked in the head.