I've seen many people offering to build your links through forums. How does one carry out the service...sign up for multiple accounts on a forum? Obviously, there are some ethical issues involved. For instance, the primary purpose is to build links to a site, not to engage in discussions out of genuine interest. Of course, I may be a bit pessimistic here. What are some justifications for the legitimacy of forum link building services?
They register members, get a profile home page link, don't need to post. I get them joining my forum and ban them. I sniff them trolls out good, they seems to have similar habits. All my forums profile home page links are hidden from Google anyway just to make sure those grubs get no link juice. So if you are buying you better check on that. I believe if you post and have a sig link that's a fair exchange, you join, add content and in return get a benefit (a link). Spammy posts need to be watched to, like the old "Hello I'm new etc" unless invited of course like I do where we have a Welcome Thread and say So be careful.
Forum signatures don't give the best 'links', but they are pretty good when it comes to sending targeted traffic to your site. They need not even be dofollow links but can send you traffic if you are posting in the right niche. That said, the type of service you are planning works like you described.. Register, Make Signature, Make 2-3 posts, Forget you ever made a login on that forum ;-)