I have to admit I’m guilty of this from time to time when I see what I believe to be cosmic (karmic) justice.

schadenfreude (scha·den·freu·de): / SHAHD n froi duh / (always italicized)
noun

(1) smug or malicious satisfaction or pleasure at someone else’s misfortune; gratification or delight obtained from the troubles of others

[From German Schadenfreude, formed from Schaden (“harm”) + Freude (“joy”).  The word may be capitalized as is normal for German nouns.]

Usage: One could not help but feel a wee touch of schadenfreude when Donald Rumsfeld lost his job as the U.S. Secretary of Defense.