[b][i]Are there "good" RPs?[/i][/b]

Well...yes and no. 

"Good", as multiple people have already stated, is subjective. It's an opinion, and like every opinion, the definition of "good" fluctuates with each individual. One person might think seafood is "good", while another thinks pizza is the best thing in the world. Is one of them wrong? [s]Yes, because pizza is life.[/s] No, of course not. Opinions are supposed to vary and contrast with eachother. It's how we make decisions and improve. If everyone agreed that their favorite color is yellow, then we'd be living in a piss colored world. 

Now, that's not to say that there's no common agreement on what makes something "bad" or "good". I mean, how many people out there would actually agree that the cringe-worthy classic 'My Immortal' is a literary masterpiece? Not many! And the few that do need a good shovel to the head. We define works as those--and let it be noted I'm using that term lightly--as "bad" because they don't meet certain standards that we describe as "good". These factors aren't all the same. Some people expect masterpieces while others just like whatever seems okay. Horever, there are, in regards to RP, several factors that are mutually agrred throughout most of the community on what defines something as good or bad.

[list][*][b]A Fun Idea[/b]
[indent]An RP can't be considered worth your time if it doesn't have a story you enjoy. It has to pull you in, make you interested, and give you somehting to work with. What would be the point of jumping into a story with a setting that bores you? Ideas differ, though, and so do some people's opinions on certain stories and cliches. 
Opinions on ideas can differ, and that's alright. But if there's an RP with ideas that seem interesting and smart, then chances are it's gonna be a "good" RP.[/indent]

[*][b]A Fair GM[/b]
[indent]Rolepayers need someone to guide them. Someone to push the plot when it's slowing down, or keep players from bickering in the OC or IC, or uphold rules when players are getting frisky. That person is the GM. 
A "good" RP cannot function without a "good" GM. What makes a "good" GM? Like an RP, the factors usually change. But the main points arenthat it usually includes someone who, while firm in upholding the rules and keeping the players in check, is flexible, especially with ideas.[/indent]

[*][b]Active Players[/b]
[indent]What's the point of RPing if you've got no one to do it with? RPers are the life blood of an RP. They provide the characters, give ideas, and can even drastically change the plot. Their decisions affect the story as much as the GM's. So if you've got a cast of people just awkwardly standing around too scared to talk to each other, then it won't be as fun. Most RP's that last and/or are enjoyable involve communication with the players and GM. The exchange of ideas will not only spark inspiration, but bring the group closer to gether and make the whole experience just plain fun.[/indent][/list]

Are these the only factors? No! Hell, you don't even have to agree with them to describe an RP as good. What makes it good is if you enjoy it, and if you think it's good. Theres no strict rubric or time limit to jjudge it. It's like when you read a book or watch a movie or eat a meal. If you think it's good, then its good.