During my usage of Drupal I had almost negligible amount of comment spam. About one or two per month. Those comments were usually containing some links to not so useful web pages. I got used to removing those comments manually. After running my website on WordPress for a few days I got about 10 spam comments. Still no big deal. But on the last two days strange comments started to appear. Usually in the tone of ‘what a good website’ or something like that. Users homepage link was set to main page of either google or facebook or something like that. Also users e-mails were real. I did check out some of them for curiosity. There were hundreds of comments like that. This was really annoying. Looking around for possible captcha solutions, I did find out that also some wordpress captcha implementations did not protect from this kind of spam. Had to resort using reCAPTCHA. This at least stopped the spam flood. A slight inconvenience to commenter though.