Are you born a Legilimen

Is Legilimacy a Dark Art? Is it legal

"The mind is not a book that can be opened at will and examined at will. Thoughts are not engraved on the inside of the skull for every intruder to read. The mind is a complex and multilayered thing ... It is It however, it is true that those who have mastered legitimacy can, under certain conditions, immerse themselves in the minds of their victims and correctly interpret their results. "

Severus' use of the word suggests an eerie connotation with the use of this magic, but this could just be Snape's pessimistic view of life.

Given that Dumbledore is a seasoned Legilimens, it probably isn't considered a dark art. However, it is likely to be regulated in some way. The Harry Potter Lexicon makes this observation:

However, we do know that Veritaserum's use is restricted by law, and we've seen Snape and Dumbledore work together on emergency (GF35) use with no apparent reference to such regulations.

Given the invasive nature of the spell, it is very likely that the use of legitimacy would be considered unethical unless deemed necessary. Snape and Dumbledore had a wrong reason (healing potions) for teaching Harry Occlumency (through legitimacy) and asked him to be discreet about what was really going on. Maybe it was because teaching a student was seedy, or maybe they just didn't want Voldemort to find out they were trying to protect him.

If legitimacy is illegal (or restricted by law), it is possible that Snape is guilty of abusing his skills in the field. In all of the books, Harry has the impression that Snape can read his mind. It is possible that he read his mind.

Dason

The reason for saying that Harry took healing potions could not be that Occlumency / Legilimacy is unethical. It could just be that they don't want anyone to ask Harry why he needs to learn Occlumency (since the reason is that they don't want Voldemort to invade his mind) and that it is a natural alternative, a false other Give class. I think the alternate class that are healing potions is in part something that Snape threw in for his own pleasure.