Lately my documents dissolve into misinterpreted Unicode, for example α becomes \316\261. What could be the cause for that?
Emacs uses some heuristic to guess the encoding of the file. In this case it fails. No problem, just let Emacs know that the file uses
UTF-8 encoding. You can do that after visiting the file with
C-x RET r or
M-x revert-buffer-with-coding-system. See
(info "(emacs) Specify Coding") for details.