My biggest disappointment ever with a purchased tomato was a few years back when we stopped at our favorite farm stand (in Wisconsin, just over the border with Michigan) fairly early in the season and bought a couple of huge, beautiful-looking tomatoes that turned out to be completely flavorless (and didn't have the best texture, either).
I'm sure they must have purchased them somewhere just to kind of round out what was available at their stand early in the season. (Mostly what we buy there is sweet corn to freeze, which is always excellent.)