I buy items off my son's teachers' wishlist each year to hopefully bribe them into treating my son well throughout the year.

Don't get me wrong, I want to help them out, make sure the class has all the goodies they need, and ensure they aren't lacking for educational materials, but I also drop a few hundred bucks each year, hoping that it will earn a little grace each year.

I don't know how much it helps, and bribes are fleeting, but there seems to be enough evidence that if you do something nice for folks, they will return the favor. It doesn't always work, and we've had our usual share of good and challenging teacher interactions. It's also not something I can easily A/B test, but it's my hope that, in the same way a utility just tends to work, in the background the investment is paying dividends.