It seems spammers have found a way to work around spam filters using the URL in the user profile. This can come from the Home Page field in the form that unregistered users must fill out (the following image is from Android Enthusiasts):
At least one user (see here) has exploited this by posting a very short answer (10k only) without a spam link, instead taking advantage of the website field in the user profile to link to the spam website, in an attempt to score SEO points for the website. Any ideas on how to address this?
Here's a clearer illustration on how it works: