I know what you mean! Not too long ago, people were talking about "Mr. & Mrs. Smith", but only because of the sound of the gunshot scenes (and of course, Angelina Jolie). I guess the movie itself was bad, but worth watching just for the sound.
The other day, I bought "Weekend at Bernie's" (one of my favorite 'guilty pleasure' movies!) on DVD and was disappointed that the audio wasn't remastered to 5.1. Yeah...like "Weekend at Bernie's" really needs a 5.1 soundtrack!