Mojibake
I wasn’t aware that this had a name until I happened upon this wiki page, but it strikes me as the kind of annoyance that deserves a name of its own. Mojibake is “the happenstance of incorrect, unreadable characters shown when computer software fails to render text correctly according to its associated character encoding.” Often, it manifests as square boxes in place of unicode characters. I’ve also encountered random gibberish like “åŒã” in place of apopstrophes or quote marks. On some occasions I’ve even abandoned pages because every occurrance of the apostrophe was translated into unintelligible crap, and I couldn’t find the right character encoding for the page.
Anyway, I feel irrationally better now, knowing it has a name, even if only in Japanese.