oddsod - 5:04 pm on Nov 8, 2010 (gmt 0)
Profiles on my forum are invisible to guests/bots and send a 404 header... for precisely this reason i.e. f###*rs that attempt to waste my resources and water down my quality website by creating fake registrations and try to ride on the coat tails of my hard work.
Profiles can sometimes be a good source of traffic (if you've got members who are well known in the industry).
What works very well for the forum in my profile is blocking new members from editing their profiles till they've made a certain number of posts and have been around for a specific amount of time. Some idiots create their profile and keep coming back to edit it later, but find that they never get editing privileges. And they keep coming back again and again, he he. I feel terrible for wasting their time :)
Since it's difficult to get post count (we have a very high anti-fluff threshold), these spammers end up never getting access to their profiles. Periodically, I delete all zero post accounts.