To be honest, I'd side with TXCraig a little bit on this one from a though process. Shouldn't EVERY pizza be one of the best they can make? I mean, if they're willing to let quality slip, then they probably don't deserve (or no longer deserve) to have the reputation that's been said of them.
It's unfortunate, but there's definitely a few places near us that served at least ONE great Neapolitan pie, and then our follow up visits were mixed results so we no longer go there.
While every pizza may not be perfect, it should be high enough quality that people shouldn't be able to say "that must have been a bad night for the restaurant" or something to that effect...
If/when I open up a shop, I'd like to think that every one of our pies is high quality and consistent... (which while will be hard pressed thing to pull off while I"m not at the helm, will be my goal as I push my partners towards perfecting their skills and QA.)