Can't figure out character set

I'm dealing with an HTML document that contains a special character that is not being displayed correctly.

My usual response to this type of problem is to, in Firefox, switch character sets until the special character displays correctly. But in this case, that approach is not working. They all look screwed up.

Here's the page in question:

http://files.mattalexander.me/c开发者_Go百科harset-test.html

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If that character is indeed supposed to be 0xEFBFBD, then it is displaying correctly for me - it is the "replacement character":

used to replace an unknown or unprintable character

See wikipedia

What seems more likely to me, is that somewhere on its way to your test page, the encoding has gotten messed up, thus the default replacement character.