I don't usually worry too much about tastes of food, either--I just try to offer him balanced meals *most* of the time. That said, he has had tastes of ice cream (which he hated), a few sips from a strawberry smoothie that the guy at the store promised me had no sugar, but instead it had artificial sweetener (ick!), and a slice of apple pie at thanksgiving. The pie was vegan (he hadn't had dairy yet at that point) and homemade, so it was basically flour, sugar, and apples, but still...
Oh, and dog food...sand...mulch...leaves...etc.