If it's not something they'd already be familiar with, especially if it's a custom thing, absolutely. Assuming I can find an image that does justice to the feel I want the monster to have.
Also, if i want my versions of the monsters to have a slightly different ambiance than the standard interpretation - i.e., if I'm running Tucker's Kobolds instead of Meepo, you can bet I'll be flashing an image that paints them more like a pack of vicious, slavering, cunning humanoid velociraptors rather than cute little anthro lizard-puppies.