when does a restaurant deserve a 2d chance??
you are disappointed in a meal or a particular dish. do you ever go back to that rest. again thinking that they just had an off night and that it might be better the next time??
If a restaurant really fails me, then I make the effort to tell them what I found not satisfactory.
THEN, if they listen and make a sincere effort to understand me, I will give them a second chance. In most all of my experiences, the second-chance try was a much better experience.
When the restaurant is in my neighborhood and there aren't any good options for a similar cuisine nearby. To me, being able to walk to a good restaurant is worth giving one 2-3 tries before I give up.
Other than that, I'm usually reluctant to give restaurants that didn't impress me a second chance, because there are so many excellent restaurants where I live (San Francisco).
Sure, if I've heard good things from others whose taste I trust, or if the dishes at other tables looked amazing, or if I just feel like it. Probably not if it was just underwhelming, or everything looked about the same quality, or I didn't enjoy anything about it.
For example: there's a place in my city rather famous for its meats -- pulled pork, lamb ribs, brisket, pork belly, duck tacos, etc. -- and my foodie friends all just RAVED about it. My first time there the pork was delicious but about 2/3 fat (yes, I mentioned it to the server and yes, they fixed it). Of course I gave it another chance. But on the other hand, I went for happy-hour drinks to a neighborhood place that was apparently trying to be the TGIFridays of gastropubs, a few months after it opened. Nothing was bad, in fact some of it was pretty tasty, but it was just so boring: ass-kissy servers in matching bland uniforms, mediocre beer brewed in-house, bacon on everything. Snore. A place like that doesn't get another chance.
only if a close friend really wants to go there for something that's important to them - my friends are more important than ensuring that I always go out for an awesome meal