I developed a strategy for that, but it is not complete.
- I use captcha for user registration and message posting.
- I removed all the additional information from user registration, so that they cannot put links and garbage on my website. That's their goal.
- First comment/question is moderated (even though I don't get many fake users trying to post comments/questions)
- This way the fake users have always 0 points
What I really need now would be a plug-in that allows me to bulk-remove users that have been at 0 points for, say, a week (or even a plug-in that does it automatically). Anybody implementing such a plug-in would save my day!