Question About "Visitor Messages" and posting links in them...

Many .. many.. umm i think i need to say it again.,. MANY vbulletin forums allow their users to post Visitor Messages in their user profiles.

By the way this is an awesome backlinking strategy, but I am looking for an answer to the following question:

What do forum admins/moderators SEE when a user posts a visitor message on someone's profile? Is it obvious?

Because I have found that if you create an account, let it age for a few days after the admin checks it out for signature spam, and it doesn't get banned, then I will go ahead and create visitor message links on other users profiles.... but... I don't run a vbulletin forum, nor want to, so... anyone with the answer - help me out

So there is no one out there that can help me answer this?