Often you will see Forums for sale with tens of thousands of members plus a high through-put rating(something that says the forum have active postings).
How to some of these forums accomplish such high readership?
Now interestingly to get this far, they have to enter a valid name & email address, plus they need to defeat a CAPTCHA and finally need to reply back to the email that is sent to them.
So either they have some fairly sophisticated software/scripting to perform this process or they are doing it manually in which case it is costing them money.
After all that hard-work, they ultimately end-up being caught in a massive honeypot sting.
So the moral of the story is, do not believe everything you read or see on the web and if something seems too good to be true, then usually it is.