Some wizards seems more immune to this than most others, though the first time exposure would have a stringer effect. Men who are exposed to it over a period of time become more resistant to it, although the Veela charm takes full effect if the Veela surprises the man. As no men of Veela descent have been portrayed in the books, it is unknown whether they would also have this ability. Veela are always, and under any circumstances, physically perfect, graceful and flawless, without anything that would make them look unattractive or distract from their presence. They are perfectly aware how to increase their appeal by apparel, action or choice of words, but even these are simply details to enhance their natural appeal.