I also had a problem like this and I want to thank aditsu for his answer.
I am using restlet on top of a Jetty server on ubuntu 12.04 (and 14.04). The restlet application is behind an Apache server that functions as a proxyPass.
All files are UTF-8.
All HTTP-responses have Content-Type text/html; charset=UTF-8.
All files contain <meta content="text/html; charset=UTF-8" http-equiv="content-type"/>
The strange thing was that when the server boots and I visit the site, the character encoding was not UTF-8 so I got all those funny characters. Even when all signals were telling the server and agents and everything in between that UTF-8 is de encoding used.
When I restart the service manually after the server boot all characters are fine. Because I could not find an answer easily and I did not know who was causing this wrong encoding I kept restarting the service manually.
My candidates at that time were: Apache, Ubuntu service boot order, Restlet framework, File encoding actually used, HTTP headers, HTML meta tags. But all were as it was supposed to be.
So in the end it was Jetty which I only considered just now after having revisited this issue several times.
I still do not have a clue why starting at boot time makes the character encoding all wrong and after a manual restart of the service the encoding is correct. Adding the extra JAVA argument '-Dfile.encoding=UTF-8' made it all go away. Thanks to aditsu again for sharing his solution!!
Cheers
Edit:
Settting the LANG environment variable in the start up script also solve the problem. I.e.
export LANG=en_US.UTF-8
Actually this is the difference between starting the Jetty server at boot time (LANG is not defined out of the box) and starting it from a shell. So two solutions for the same problem.