Comment 66 for bug 228988

User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.11) Gecko/20101013 Ubuntu/10.04 (lucid) Firefox/3.6.11
Build Identifier: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.11) Gecko/20101013 Ubuntu/10.04 (lucid) Firefox/3.6.11

Full, detailed story: https://bugs.launchpad.net/ubuntu/+bug/228988

Since I'm using it, I see Firefox (2.X and 3.X) *sometimes* display pages using the wrong character encoding. Sometime a page will display correctly, later the same page won't, without any apparent reason, nor special action. However, I have found a procedure that's reproducible on all my systems, including freshly installed, e.g. Ubuntu Karmic as is, but unfortunately not on all other ones (mainly US ones).
display http://atilf.atilf.fr
Click 'Entrez dans le TLF'
Fill in search field: 'erreur', click 'Valider 1'
Select the word 'ERREUR', a window pops up
Click on 'le TLF1' in that window
The pop up window invariably displays ISO8859-1 as UTF-8 as shown in
http://launchpadlibrarian.net/55706907/Screenshot-Mozilla%20Firefox.png

See more details at the Ubuntu launchpad URLs.
Sorry if the questions I was asked there made that report a mess.

Side notes:

It is a bad idea to specify the character code of a Web page in the envelope (SMTP or HTTP MIME), because it puts the burden of modifying the page to someone who stores it to a file instead of to whoever wrote the page in the first place.

Any feature allowing the user to correctly display a bad page is not only inciting the Web authors to continue writing more bad pages but also towards the users displaying good pages the wrong way. The Web is full of horror stories by people not having understood character sets

Reproducible: Sometimes

Steps to Reproduce:
1. display http://atilf.atilf.fr
2. Click 'Entrez dans le TLF'
3. Fill in search field: 'erreur', click 'Valider 1'
4. Select the word 'ERREUR', a window pops up
5. Click on 'le TLF1' in that window
The pop up window invariably displays ISO8859-1 as UTF-8 as shown in
http://launchpadlibrarian.net/55706907/Screenshot-Mozilla%20Firefox.png

Actual Results:
http://launchpadlibrarian.net/55706907/Screenshot-Mozilla%20Firefox.png

Expected Results:
same after forcing ISO8859-1

Thanks.