Perhaps you would never have a use for a word like this, especially in reference to another human being, but bear with me. It has a particular meaning and purpose, and it’s meant to be descriptive.
If you beheld a waffle, you might in the ordinary course of events approach it with an eye to its golden brown beauty, utility, edibility and caloric density. But if that eye fell upon a corner of the waffle which had been most callously and vilely defaced by a mighty wad of snot, you would wish to pivot and flee, as having beheld something which got your hopes up and then dashed them to the extent you went from feeling pretty darned good to wondering how the hell you could have mistaken that shine for maple syrup.
When you run across a person, of any gender representation, who appears okay and, you know, a human being, but on closer inspection appears malicious and nasty, and secondarily any person who takes something good and leaves it fucked and far from home and no longer possessing beauty or utility, and who offers neither excuse nor remedy, that person, dear friends, is a snotwaffle.
I guarantee you that an occasion to use this term of opprobrium will find its way to you soon, because this poor old world has snotwaffles in quantity. And if someone calls you on it, you say, “‘s not awful, why, what do you think I said?”