Some of my friends think I'm a bit paranoid in my internet use because I avoid putting my e-mail address as a link that spambots would find. I don't spend time worrying or testing. I don't think I do any of these things except check for "https" on webpages with financial transactions and using free software to periodically check for adware.
But it's interesting what can be done, if I was actually paranoid.
UPDATE: Hm. Perhaps I should change some of my passwords. Eight letters takes a single modern computer only a short time to figure out!