Are Demonic Fairies (Half Demon, Half Fairy) Over Used or Cliched?

I don't know about demon-fairies...but I think hybrids in general are cliche. It just doesn't make sense how these creatures are even able to conceive together... Maybe I'm yzing too much, but in the actual animal kingdom, only species that are similar (like horses and donkeys) are able to reproduce together (thus, the mule) so I like it the same way with my fantasy creatures.