On our main sites "the best answer" is somewhat fluidly defined as the superposition of the highest voted answer and the accepted answer. Truth be told, the system is rather insistent on allowing multiple "right answers" and that's one of its strengths: you can be the judge of who you believe.
But that doesn't always translate well on the per-site metas, which serve as a sort of policy-creation body. People who are active on meta help decide how policies are enforced on the main site. Moderators who have ♦-powers tend to take mandates on meta very seriously. Practically speaking, accepted answers to meta-questions are no different than any other answer. Does that leave just votes to determine consensus?
Closely related: Not everyone participates on meta-sites. It can be hard to tell if enough people have looked and voted on questions for real consensus to be declared. Size of the site determines how many people could be voting on questions. What counts as a quorum?
Finally, sometimes people change their minds about a meta-question, but, since votes are locked on meta, it's not really possible to change one's mind without a pointless edit to someone else's answer. When should meta-questions be revisited?
On graduated sites, ♦ moderators are elected, which makes them representatives of the active participants, but on beta sites, we are appointed. It's doubly pressing for beta sites to determine "the will of the people" since part of the point of a beta is to get a working policy framework in place before electing permanent moderators.
I'm interested in figuring out how sites already answer these questions and what might be done network-wide to make discovering consensus a little bit easier.
N.B.: Obviously this assumes that consensus matters. It does to me when I'm making my decisions and I suspect it matters to others. But that isn't to say that it always makes a difference. I'm really not interested in answers that hope to use this question as a grindstone for all the axes stored up against certain people who have made unpopular decisions and have the power to make those decisions stick. Feel free to ask your own question(s). (Thank you.)