The ones that bypass the captcha are almost always "paid" russians/chinese people that do nothing other than enter captchas all day long (other 3rd world countries do this as well, but primarly these are the biggest 2 culprits). They make like $3US-$4US/hour doing this crap, its hardly worth it to someone in the US and many other places but its something you can make your kids do when they are home I guess. It's a partially automated process for them. Everything is automated, all they do is enter the captcha all day long. They are given a screen that shows them captcha after captcha, they never even see the forum thats being signed up for. It's a big business for blackhat SEO companies. It affects forums mostly, but can also affect CMS's such as wordpress, joomla, drupal, etc because they too allow posts that can contain links which in turn has SEO ramifications. Google has tried to put a stop to this type of stuff, but it hasnt really been able to make it pointless yet so there is still a market for this type of garbage. The best way to combat this sort of thing is to ask a logical question such as "What unit does a Town Hall make". They will never know this, but every one of us would know it.
