This normally depends on my mood. I'll resign when appropriate, but when someone assumes I'll resign, then I don't. For example, I was playing a 1900 player (I'm ~1500) and he said Good Game before I had even considered resigning. Even though he ended up with 2 pawn promotions, I still made him play it out because I hate people who assume they'll win.
Resignation etiquette

This normally depends on my mood. I'll resign when appropriate, but when someone assumes I'll resign, then I don't. For example, I was playing a 1900 player (I'm ~1500) and he said Good Game before I had even considered resigning. Even though he ended up with 2 pawn promotions, I still made him play it out because I hate people who assume they'll win.
Does this mean when you play an 1100 you never assume you are gonna win ?
A person should resign when it's obvious the game is lost.
A queen versus king should hit that threshold for anyone over 5 although I've seen people play this out in tournaments. I think its rational to be irritated when people drag out a loss. However, you do have to account for the fact that not everyone will see the loss as quickly.
More interesting is whether to accept a draw offer in a dead drawn game or to play on and hope for an error.