Yes, pure speculation. But if you ignore your given known Google links, and do a (Yes I know this is old, but what goes around etc) "linksto""yoursite" then the odds are that the search will result in Link related topics in forums. Whereas if you do a simple "counciltenantsmortgages" or the same with any site, WHERE the owner/user is a known forum player you will see that the links are still very forum related. The longer the thread the more 'linksto'.
In fact, one forum cottoned on to it, and NO I cannot say which one, but they were using their usernames as link bait for paying customers. So I think I was correct all along and that usernames and
SEO tatics go hand in glove. I would add that it was not my forum, and I thank the heavens that I did not try it. As Google has locked off those links and the posters IBL counts have been sorely disrupted.
Self Edit - I just had a e-mail alert that a thread I was in had had a reply. No big deal. But that thread has been resurrected by thedark and it is nearly two years old. Why he posted on it is anybody's guess. But I cannot complain as we tell new posters to read previous posts to learn from others. So now that a really old post is back on top, it will get crawled. Is it 'New Content' for the bots - or will they recognise it. My guess is that it will be date indexed and ignored. You???