Well, some also are on here due to Google searches that are performed so not all are of malicious intent from what I understand.
Exactly right.
How do you think Google, Yahoo, Bing, etc. get their info? There are automated bots (spiders) from all kinds of websites sniffing around the internet. Most of the time they are not malicious: they just read/follow down the web pages, create their searchable indexes, and follow down any new pages they find. If you want to show up on their searches you allow it.
I've seen entries on the corvette forum show up on Google less than an hour later. Don't know how or even if these websites decide to saturate a target website with bots. On the other hand, cost to launch more bots is almost zero to them.
There certainly are automated bots looking for personal info. Just don't do anything stupid like putting any personal info in a thread.