Everyone probably has their own idea of what characteristics define a jerk, but a common dictionary definition is a foolish, rude, or contemptible person. This may well describe some of Clark's past behavior; the question is, does it describe his current or future personality? Someone who was ignorant or thoughtless in their youth may be acknowledged later in life as a great scholar or philosopher. A weak, untrained, lazy or sick person may later be revered as a great athlete. In these cases respect for their accomplishments is often greater because of their earlier shortcomings. Is morality the only area where you can never be forgiven your past sins; more than that, admired and respected for having overcome them?
There's no simple answer to this. A court of American law might take into account the consequences of your "sin," your ability to understand the probable consequences at the time you committed the sin, your motivation when you committed it, and any extenuating circumstances. For example, in Clark's "Exile" rampage his crimes are mental cruelty to his family and friends, damage to property, theft, endangering bystanders, disobeying the law, and knowingly using a mind altering substance that could be reasonably expected to lead to this type of behavior.
Extenuating circumstances would be his attempt at restitution, his age (only 16), his state of mind at the time he took the drug (in shock, in mourning, rejected by one father and under assault by another), and the degree of contrition. I personally think Clark's determination not to be maneuvered by Jor-el into taking over the world quite extenuating, even if his tactics were questionable.
