I have Akismet running fine.
The comments are a sort of random text using a Facebook-url which can not be found (error pages) and an email-address which I can check if it's real or not. I guess the email is real and used for further spamming if these comments are allowed.
Have had this issue on another WordPress install for months now, maybe a year.
I guess Disqus will solve it, but I am not 100% sure I want that.