The Shintao Monk's prestige abilities are only supposed to work on "tainted" creatures. This includes undead, aberrations, and extraplanar creatures that are not lawful outsiders. Though honestly, how can an extraplanar creature not be considered an outsider? If there is an example of such creature, I would like to know.
So I'm going through the vale and doing some slayers, and I find out that apparently orthons and bearded devils count as tainted creatures. How can this be? All devils (or most at least) are considered lawful and therefore should not be effected by my jade strike and smite tainted creature abilities, yet I can use those no problem on them.