Exactly, the ick is an instant change, it just happens and over something random often. It's not the attributes you don't like in someone.
I had it once with someone I really fancied, had wanted to date for ages, was great for s couple of months he then just said something random during sex, nothing offensive at all but it was like a switch turning off and I didn't find him attractive at all.
I think I am prone to getting the ick, it happens all the time to me. It's never a gradual thing, one minute I fancy them, the next I don't.