Waittaminnit… There are professional dog food tasters?
My horrified thought exactly…
Reminds me of a Gallagher routine, about who decided to make cat food in the shapes of the foods they were supposed to taste like.
Why do they have people trying dog foods? Shouldn’t they have dogs trying dog foods? I mean, who cares if I like it or not, as long as Fido does?
OTOH, my best friend and I used to occasionally eat Milk Bones when we were kids. Good for your teeth! 
The Cat In The Hat
I think David Letterman was a dog food tester, not sure, but he did have one on his show with different cans for show and eat. Much to the publics disgust, Letterman gets a spoon and also digs in. Hes done this many times before (dog food eating) in his early days. Also there was a TV expose about dogfood testers, explaining how those Purina/Puppy Chow commercials hire people to critque their work and hence the, “7 dogs out of 10 prefer our horsemeat over theirs”.
As to the original question, the answer is the same, in general, as that to any other attribute of a human or other organism: Evolution has to experiment because it never knows how the environment will change, and if it didn’t, it wouldn’t be evolution. I mean, that’s what it gets paid for. 
But I don’t think my tastes in food have evolved with age. I’ve always like all common vegetables except raw tomatoes. Eeyyaachch!!! I’ve tasted them recently at age 68. Still no go. I rip them out of all sandwiches that have them. I don’t mind cooked tomatoes, and spiced tomato juice I rather like. I guess I don’t know what okra tastes like. I’ve never consciously tasted it.
Definitely, usually rather bland or unsavory food tastes far better after extensive exercise, such as hiking in the wilderness, and tasty food tastes scrumptious. Even without the exercise, less tasteful foods are more welcome at the beginning of a meal, when you’re hungry, than after you’ve easten a bit or have eaten richer foods.
So dogs have to eat foods that humans like these days? What do the “diversity” people have to say about that? Seems like that’s carrying the melting pot a little far. Do people also taste-test cat food? I don’t think that would work very well at all. Hey, maybe, instead of shooting rogue bears these days, they could employ them as dog-food tasters – or maybe even human-food tasters. ‘Tops by taste test! Ripped out of more cars in Yosemite than any other brand.’
Ray (Mmm, mmm. . .no commercials while eating.)