I have two that wont eat F/T. The boas were started on em and I dont know if they would even know how to do a kill strike (Ok they would, but they get so lazy about taking the F/T ones in such a casual way) and Im fine with that!
Two of the corns ate F/T from the first feeding. One didnt eat for two weeks, til I offered it a live one, and one held out for a month (Miiha of course) til I gave a live pinky a bath with unscented ivory soap. Ive just gotten her to the point she will eat a live pinky without washing it first, but since shes still on the skinny side, I havent switched her yet. Operitive word...Yet. Mr Noodle will sometimes eat a frozen thawed now. Its sort of back and forth. With six snakes, a gecko and mice its definately time to get them all on F/T.