Before getting rid of the obviously less-than-palatable first test item, Crunch'n'Clean, I decided to do an experiment. I laid down four treats and invited Kenya to partake. The one closest to her was Crunch'n'Clean, the next, a no-name from Costco with the same ingredients as her kibble, , the third one a Marrow Bone, and the fourth, a piece of a dried chicken breast, also from Costco. I made sure that all four were roughly the same size so that she would not be lured by gluttony. All four were approximately the same dull tan colour so she would not have been tempted by what might have looked good.
Kenya sniffed each one in turn and then picked up the one furthest away (the chicken), and ate every crumb. Then she chose the next furthest away, the Marrow Bone, and ate it up completely as well before moving on to the third choice, the Costco biscuit, She looked around for a few minutes snuffling and vacuuming up all stray bits of cookie.
Finally she sniffed the Crunch'n'Clean and licked it. She put it down on the rug for a moment and then bit into it and ate each of the pieces.
I decided to continue till the end of the week in view of the fact that she may not like it very much but it isn't something she refuses to eat, so her teeth are probably getting their daily cleaning with it.
Also ... she eats fewer treats when that is the one I offer most often.
I suspect that a gluttonous dog might behave differently. Most of the Labs I know don't care what they eat as long as it is edible, and there was that Bernese Mountain Dog puppy who didn't even care whether it was edible.
Kenya has never been a glutton ... but she does like her treats ...so she is probably a very good taste tester.