I enjoy the show, but I don't think there's been a single episode where I came away saying I'd like to eat there. In fact, even with the professional makeover, I have yet to see a single restaurant where I would willingly eat.
If a place is disgustingly dirty, a clean-up and lesson in hygiene is called for. But the chances of relapse seen high. If a chef doesn't know enough to put salt and pepper in food, which seems a common error, then they don't know enough to be in the business and will probably be making bad food immediately again. You can tell the owner to stop screaming at the staff, but you can't redo a personality without at least six months of psychotherapy. (Ha!) You can gussy a place up in two days, but most of these restauranteurs seem possessed of numerous bad habits, and I come away feeling that just about everything is going to start its slide from mediocrity nearly immediately.
And here's the thing that really brings it home to me. This show often runs right after "Diners, Drive-Ins and Dives"--which features places I'd be very happy to eat in. Most of these restaurants have some signature dish or dishes that make it worth a trip. Robert Irvine may donate a recipe or two to the places he upgrades, but they're still left without any signature dish. And that's the real flaw of so many of these restaurants. If you're serving the same food as dozens of your nearby competitors are, it doesn't matter if you're now only brought back up to their level. As Gypsy Rose Lee once said, "you need a gimmick," and these places are mostly a dime a dozen.