I think it's basically the theory of democratic elections though.

That someone has to present themselves as a non-sleazy person with non-sleazy plans to get elected, and if they do something different once elected or otherwise do something the voters recognize as super sleazy, they won't get re-elected. So a person in an elected position is responsive to public opinion, or does not remain elected.

Whether it's working out so well for us in the USA, I dunno.