I think they only taste the rush from really intense favors. Mega sweet, ultra salty, fried (ideally all combined). It's why a lot of junk food can get away with using low quality ingredients and covering it up with a bunch of sugar and turn it into $$$. Take the crappiest doughnut and put an inch of frosting on it and they'll think it tastes really good. Add a frappuccino to wash it down.  Honestly if they couldn't taste they would probably just eat soft textured food like breads and cakes anyway so they don't have to chew. And they would still drink beetusjuice for the bubbles. They still wouldn't excercise and they still wouldn't know when to stop eating.