This is strictly my opinion but when someone has got me backed into a spot where all my moves are spent passing and I know there is no way i'm even going to get a move in the next 10 turns I usually resign. And if an opponent is in the same situation I don't take it against them to do the same. I guess its all up to you whether you would like to play out the game and see where it goes or learn from the experiance or if you think that you will not benefit from the game then resign. I know that I don't take offense to it when people resign and I usually write a message to the person i'm playing if I resign the game.