Loryen
Well, yes, there isn't really a line between griefing and RP, as they're not mutually exclusive concepts but overlapping concepts. Something can be both. So what I defined was not the line where RP stops being RP but just the line where RP becomes griefing, which is probably the same line where anything becomes griefing ^^I think you present not the difference between griefing and RP, but something perhaps more important...respect.
Erizon
Nah, you misunderstand me, it's not about whether fun actually gets maximised, it's just about what John's motivations were. I don't consider it griefing if he ended up ruining Jane's fun by mistake. And like Loryen says and I also did admit, the big problem is indeed we can never be sure of someone's motivations. But in my personal experience, it's usually fairly easy to make a pretty accurate guess if you just talk to John a bit. John's motivations are to make the game more fun for everyone, but John and Jane disagree on what is fun.