How do mining pool operators work? How does one get to be a mining pool operator? Is there an election by people who want to pool their computing resources? What checks and balances exist to ensure that a pool operator doesn't misappropriate funds?

This question was inspired by my comment, and a response on this question? What prevents miners in a pool from retaining the reward?
You, the miner, are the one being paid by the pool operator for doing some computation. It's a free and open market. You can switch pools if you're unhappy with the reward or the honesty of an operator.

To become a pool operator there's no election process or formal checking whatsoever. Again, it's a game based on reputation. Just like any other business, if an operator misbehaves (by stealing funds or something), they lose reputation and therefore users.