Jiminy Cricket once advised Pinocchio:
“Always let your conscience be your guide.”
That is good advice for the animated boy, but it is probably easier said than done for those of us who live in the real world. What we would like to believe is that every human being has a conscience which keeps his evil ("bad" and immoral) desires in check and therefore only acts on his worthiest ("good" and moral) desires. The problems with this thinking, of course, are many--too many to enumerate here because they are limited only by the creativity of the human psyche.
First, not everyone has the same sense of right and wrong, of what is moral and immoral. It might be nice to think that everyone believes cheating is wrong, for example, but the evidence is overwhelming that a majority of Americans cheat in some form.
[A]ccording to a 2002 confidential survey of 12,000 high school students, 74 percent admitted cheating on an examination at least once in the past year.
Nearly half of all adults in a recent poll have admitted to being unfaithful at some point in their lives. Add to these numbers those who cheat the government by lying about their taxes or who cheat nominally by keeping the money when a cashier gives them too much change. The reality is that we do not want to be the victim of cheating in any form, but we somehow believe that if we do the cheating it's victimless and perfectly acceptable.
Second, we are always trying to justify our own bad behavior by looking for exceptions to the rule which make our bad behaviors acceptable. While other people should have to make a complete stop at a stop sign, for example, we don't need to do so because we have a clear view and can see that no one is coming. We know this is simply a justification, a moral compromise, because if a police cruiser is sitting nearby we are sure to be on our best ("good" and moral and correct) behavior.
Third, we want what we want, and demonstrating self-control (self-restraint, moral consistency) is much more difficult than giving in to our wants and urges. Let's face it, Americans are notorious for indulging today while vowing to "work it off" or "pay for it" tomorrow. This can apply to food and overeating, of course (something we all know is not a "good" behavior), but it is also applicable to our spending habits (misusing credit to gain something we cannot afford), our work ethic (taking advantage of a lenient boss or access to supplies which you assume will never be missed). Again we justify our behaviors, but most people do know that these things are not "good" behaviors.
Finally, from the perspective of my worldview, we are all born with a nature to sin (do "bad" things). Watch a toddler lie when he breaks something and wants to avoid punishment, watch him refuse to share something he wants for himself, or watch him take things that don't belong to him simply because he wants them. While these are teachable moments are rather excusable for a toddler who has to learn to tell the truth, to share, and not to steal, they do demonstrate the innate desires we have to do exactly what we want, even when we know it's morally wrong.
Lots of factors come into play in any discussion of morality and consistency, but in general we ignore our own morals (our personal standards of "good" and "bad") when we give more weight to our desires than to our principles. Life is full of temptations that we must all face, and living consistently within our moral code is a challenge for nearly everyone.