Experience - the wisdom that enables us to recognise in an undesirable old acquaintance the folly that we have already embraced.
It has long been known for sure that the sight of tasty food makes a hungry man's mouth water; also lack of appetite has always been regarded as an undesirable phenomenon, from which one might conclude that appetite is essentially linked with the process of digestion.
Sometime they don't let you know that they know that they don't know everything, but the core of the medical approach is that you try to identify pathologies, which are subsystems within the human body or the larger system that are having undesirable consequences.
My own view is that this planet is used as a penal colony, lunatic asylum and dumping ground by a superior civilisation, to get rid of the undesirable and unfit. I can't prove it, but you can't disprove it either.
I suppose I have very undesirable traits. I am very critical, which is very undesirable. But it is good from a business point of view.
I was always good at math and science, and I never realized that that was unusual or somehow undesirable.
As a result of my study, I came to the conclusion that a common supreme authority was undesirable.
As smart technologies become more intrusive, they risk undermining our autonomy by suppressing behaviors that someone somewhere has deemed undesirable.
In the beginning of the human race there was no genetic load which would cause undesirable traits such as appear in offspring of marriages between relatives today.
The stigma that was once attached to things society deemed unhealthy served the purpose of making them undesirable. With the stigma gone, many people see little reason not to do whatever feels good at the moment.