IF you can affect them, see Aurora and Lea. I'd think you'd need to be an expert in fae psychology or way more powerful than any mortal to even begin to affect them by anything but luck or having some means to cheat.
Leah (and to a lesser extent Aurora) are pretty much near-godlike in power, and as such can't be the template for all fae creatures when it comes to mental sturdiness. Could you mentally blast a pixie into something they're not? Possibly. Could you mindwipe a Hob totally, causing its lack of self image to make it disappear into non-existence? Maybe (provided you get a takeout). So fae that aren't so powerful as those two should be able to be affected.
Unless when you said, "I'd think you'd need to be an expert in fae psychology or way more powerful than any mortal to even begin to affect
them by anything but luck or having some means to cheat.", you meant "
them" as in Aurora or Leah only, not "
them" as in fae in general. If you meant the former, I agree.