Good eye Dave,
I've been watching these too and baiting a few potential users to see why or if something will change or tip me off. I've wondered why there are no link pointing, especially with the recent new member that caught both our eyes. The one in question, registration profile doesn't' suggest anything troll like or spammy so far but I never noticed the signs you've picked up on in the writing style.
I've been noticing a new spam bot that is learning our registration requirements. They are onto us. Its got me quite concerned so I've been changing things more frequently this past month. Now our female user is appearing out of the blue. If its a bot, which I think may be, may find this thread and tip us off. If not, then forgive us for being careful and protective spam hounds
Good for your detective work.