An RD factor for the civility rating ?
Civility and Sportsmanship
I like the reputation idea, where you can give someone plus or minus reputation based on how courteous they were.
Sure, it can be abused, but if you only allow a player to vote once for or against another player, I think the people using the system responsibly would outweigh the people using it in an abusive manner.
Earlier today I played a great game with another player, it was a very close and intense game until the other player made a blunder that allowed me to eventually take his queen. He quickly typed "lol I win, fish..." and then resigned, it completely took the spirit out of what I thought was an entertaining game. I would love a system where I could publically rate my disapproval of his childish attitude.

Why not just thumbs ups? Surely a lack of thumbs up would be just as telling without the need for negativity.
When the Romans wanted to endorse something, they gave it a 'thumbs down'. By contrast, 'thumbs up' meant they thought you sucked. (See reputation-system)

Some poker sites suspend chat priveleges for rude behavior. The suspended players can still play, but they can't chat. If the the player offends again after the suspension is lifted, then a longer or even permanent loss of chat priveleges can be imposed.
Most people here are not rude. I haven't had any problem in the short couple of weeks I've been playing here.
We should all encourage people who are pleasant. Give positive comments and feedback. Make a friendly greeting at the start of the game. Give good sportsmanship trophies. Chess.com is a great place to play. Let's keep demonstrating good sportsmanship and I believe the rude people will remain a small minority.

I like the reputation idea, where you can give someone plus or minus reputation based on how courteous they were.
Sure, it can be abused, but if you only allow a player to vote once for or against another player, I think the people using the system responsibly would outweigh the people using it in an abusive manner.
Earlier today I played a great game with another player, it was a very close and intense game until the other player made a blunder that allowed me to eventually take his queen. He quickly typed "lol I win, fish..." and then resigned, it completely took the spirit out of what I thought was an entertaining game. I would love a system where I could publically rate my disapproval of his childish attitude.
Funny. I would probably refuse a rematch with anyone who kept playing for a significant length of time after they blundered their Queen.

Why bother with thumbs downs?
Why not just thumbs ups? Surely a lack of thumbs up would be just as telling without the need for negativity.
I would want both. Sometimes I don't feel one way or the other. Sometimes I feel strongly plus, sometimes strongly minus. It's really more of a "rate from 1 to 10", in principle, but within simplicity is elegance, and therefore greater adoption.

the biggest advantage of a civility system of any kind, would be the simple fact that it exists.
the ideas behind its logistics aren't nearly as important. sure it would be nice to know who the jerks are and be able to avoid them, but the real goal is to make there be less jerks. hence the acompanying proper use and conduct letter that should be sent out to all current and new members.
Just making people be aware that they are supposed to act civilized on this site and will be held to its standards should be enough to cuase the change we seek, and keep the live play feature from falling into yahoo chess status. Becuase honestly, this is the place I came to to escape from yahoo chess, and I pray that I will never want to escape from here the same way.
I wondered when I first started on this site why so many people disabled chat immediately at the start of a live game...
After a few months I don't wonder.
Somedays if I'm in a troll-baiting mood I leave it on, but honestly the best way to deal with it is just to disable chat on all your live games... Just my opinion.

Solution to your problems: become an NM. People generally speaking are very curteous to me, even in live chess.
If only. :-D


Many disable chat, even for quite valid reasons. We should be given the possibility to send and receive standard phrases ("Good luck", "gg", "well played", etc.) even keeping the chat disabled.

One could also make the argument that subsequent thumbs-down ratings could have less effect, a decay variable if you will. Build into the system that if I'm giving someone a thumbs-down and its my 50th thumbs-down in 2 days, but if someone else does it, and it's their first one, then theirs counts more.
Maybe it's unnecessary complexity.