For non-sandbaggers, sandbaggers are, at best, a nuisance and lend to a negative experience (at least for the sandbaggee).
I propose an opportunity to anonymously click a box following a game, on whether you believe you’ve been sandbagged.
Similarly, in creating a game, there would be an option to prevent those who have distinguished themselves as sandbaggers from accepting.
I think these two “enhancements”, which have relatively unsophisticated implementation, may help provide a better OGS experience for kyu players. While this may not work 100%, it would help put a negative spin on sandbagging that I think hasn’t been addressed in any way so far.