I'm a big fan of Guy Fieri's Diners, Drive-Ins and Dives. He's not a hard hitting food critic (and I'm not sure if he even qualifies as one), but I always thought that the best time to dine at a restaurant was when Guy Fieri visits to film. His visit won't be a secret thing since his show is highly publicized, so you have an idea of when to visit. And when do you visit, you know the owners will do everything in their power to make sure their restaurant is as clean as possible, that they're using the freshest ingredients, and that they're at the top of their game.
Fun article, if a bit longer than it needed to be (too many examples of restaurants trying to make things super-shiny for critics IMO). My partner is a manager at a big retail chain. C-levels occasionally like to make "unannounced" visits to random stores to see how things are going. Days before the C-level's flight arrives, managers know about the visit and are working crazy overtime to clean things up.