The key error you, and many well-meaning prior commentators have made, is in misunderstanding the role demographics plays in the way modern professional spammers target forums. Your comment about spammers targeting tech forums is revealing, and somewhat naive.

Users here are affluent, very active on the Internet, and much more likely than average to bank online BUT they are often older and LESS technically sophisticated than the average person with equal net access and are naive with respect to online scams. If you've lurked here much, surely you realize how very naive and gullible some of my users are?
Just so you know......here is the tech forum I was talking about:

http://forums.techguy.org/

As you can see if you browse through there a bit, many many of the people there have barely enough knowledge to turn on their computer........it's why they come to us. Because they need help because they don't know what to do with a computer and have either messed it up badly themselves, or have been scammed or have horrible malware on their computers. So, because of the questions that are posted on our site, we have many spammers and scammers targeting our forums, plus, we have, several times, been specifically targeted ourselves for DDOS attacks from these people precisely because we help prevent those types of things and help clean up computers and help those that don't know how to use a computer. As a matter of fact, the majority of our users (according to profile information) are older people (over the age of forty).

Traffic here is more than most people -- including Alexa -- realize. And it's up a bunch. (Apparently, some of the spammers do know -- many of the spam attempts lately have been by SEO hired guns.) We have an ENORMOUS number of lurkers. ........6 or 7% of the traffic PF was handling at that time. I need help in this area, but I've quit asking, because virtually all the the responses I've gotten in the past miss the mark so widely.
As you can see, the forum I was referring is so large that PF itself would be maybe 6 or 7% of it's traffic. Our forums are actually running on six servers now, just to handle the traffic. As I type, there are 3,679 active users,.....and it's a slow night.

Well, back to the spam topic, here is what we use on the tech site:

http://www.vbulletin.org/forum/showthread.php?t=248042

I take it, however, from your response that you don't wish to have any further suggestions or help in this from lil ol' me, so I'll not discourage you any further with my naivete regarding spam and forums and stick to posting about pools.

Have a great night.