Is it really so hard to make it next to impossible for bots to create those zombie accounts? I mean captcha codes, logic questions and things like that?
There are services online that bots can use to bypass captchas and such by getting humans to solve them for a small price (this is what the majority of captcha solving jobs in the Services section are). This is near impossible to stop, as it is essentially undetectable by a server (it looks just like a real user solved it). There is no real way to stop bots registering, the only way to beat them is through moderation.
I hope this issue has been dealt with properly if it really existed.
I feel the moderators do a very good job in stopping bots from making a mess of the forum, the fact that you didn't know they existed proves that. The vast majority (if not all) bot posts I see are deleted in under a minute.
Anyways, such accounts could be totally excluded from consideration...
Say, all accounts without a post history
That sounds better. It would still include the huge amount of shill accounts around the forum, but is probably one of the best estimates we can get of the whole population.
