I fear we hijacked the thread. Sandbagging is not quite on topic here. Maybe these messages should be moved.
However.
I do not quite can wrap my mind around this idea.
So… to resign a won game, in order to win later a game. This is insane.
Any sane player want to play with good players. to learn to advance. to have interesting games.
The pleasure is in the struggle to win, not in a win without meaning. And this is true for any game. Once I found a hack for an RPG game. I enjoyed briefly the idea of an easy advance, but in few minutes I got bored.
So, anybody looking for an easy win has a problem. Maybe just a regular frustration, or worse. So let them win till they get cured. I am personally glad to be sandbagged.(unless I am too tired to play, and actually think) In a way sandbagging is free teaching, so is good 
Many pay money to play with better players.
And actually speaking of teaching and throwing games, I realize that I am a sandbagger myself. At one point in the progress of a student may need encouragement, and slip a win, not actually deserved. And is quite hard to fake a loss and make it credible. And if the student gets cocky, then crush here it comes.
I even have a story in this subject. It was not quite a student, but a newer player. Smart guy, advanced fast but my decades of experience still kept me ahead, even I was plateaued at 4 k. Obviously there was handicap games, and at even games even the score was close, the win refused to come. I always felt him behind, never make me feel in danger. Until one day when a win came for good. I did not threw it. Maybe I had a bad day, or he a really good one and he won. Nothing wrong. And I usually do not mind losing. But he started laughing, and very confident stated that from now on I am his victim. I got actually annoyed, and without thinking, I reminded him that advancing in Go is not so easy, and my years of experience have a lot of weight even I never studied. And I promised that he will not be able to catch me sooner than two years. He was not so far behind me so my bet was quite a hazard. For me was just words thrown at anger but he took it seriously. Now and then we clashed, he grew, games were harder, but somehow never managed to beat me in those two years, even as strength he was at my level in a year or less.
Anyway, conclusion. Sandbagging is just disguised free teaching.