Just now, someone who definitely did not have JS disabled, failed because of the hidden captcha. I was tracking his attempts to comment because he failed earlier and I had no explanation why. This is what I found in the spam_bee.log for said attempt to comment, and the part in bold does look a bit strange to me:
Hohum. Looks like an encoding issue of some sort. My blog is running on UTF-8, but maybe there's something wrong with the part of the Spam Bee plugin which generates the hidden captcha? I assume this is done using JS, so maybe a JS file isn't encoded properly or something?[2013-08-26 14:27:12] - [MODERATE: BEE HiddenCaptcha [ 8 != � ]] - [#46, Name
I realize this is probably hard to debug for anyone but Grischa, but any help would be appreciated.