This is expressed as the quality parameter. To make the system GP proposed work atop HTTP content-negotiation, a server operator should assign a very small number to the automatically translated content.
(Also note that I wasn't talking about automatically translated content necessarily. Manually translated content still often is of worse quality than the original language.)
It is; but also there is a server counter-part with its own quality weights. If that does not make sense, play with the code in http://p3rl.org/HTTP::Negotiate and read the HTTP spec.
