Can you give us some examples of who has done this and how they avoided getting caught on Mechanical Turk? I've had legitimate HITs removed for apparently violating policy recently, so in my experience AWS is fairly vigilant in looking out for HITs that attempt to juice SEO or promote.

I guess it could work if you abstracted it enough so that it's not apparent to the worker, but it wouldn't be trivial to execute. Using VAs on Odesk might work better.