The Zoahr states that for all sins a person is able to repent, beside someone who wastes his seed (Zera Levatalah).

Rebbe Nachman said, of course this sin can be rectified and that he is one of the few people that understand the mystery of this Zoahr.

On a simple level it means, that a person can wipe away ninety nine percent of his sin but will always have some remaining trace. This is more the good enough for the average person.

Here is one place where it might come into play. If person was ever Pogem Habris he can not join th society of the thirty six hidden tzadikim (Lamed vav Nistorim).

A person should not worry, he should try to do as many tikunim as possible and confident that Hashem will forgive him.