Have a look at the image below - a screenshot from a website I came across. It's a quite clear, massive fail (unless you're fluent in whatever font is used). This is something that can happen to any site, if you're messing with I18N or L10N - something goes completely screwy. However, it's also one of those things that - when using a professional CMS - just should work without massive headaches or hidden traps. Typo3 wants be a professional CMS, so, following the logic, this shouldn't happen (or the site author should have massive warning bells ringing).
What went wrong here? Well, several things. First off, the site uses Typo3 to generate images containing text - and uses that for links. In itself a horrible idea that's very bad for SEO but is used by Typo3 so users can get "that special font". It wouldn't be so bad though if it wasn't for the fact the there's either a mismatch between encoding somewhere in the system or the font needed can't be found or used (I'm assuming that the install hasn't been hacked and someone switched the font used to wingdings). If the system had just been outputting text and setting the wrong encoding then at least users would be able to manually switch. As is, there's just no way of figuring out what the text is supposed to be. Your best bet is looking at the html source and trying to find out by looking at the link titles - not exactly what you want users to do.
Now, to add an extra bit of irony to this: the site name is Typo3 Experts and they're hyping their Typo3 cookbook. Would you buy it after seeing this site?