What if they made it so the random timer was anywhere from 1 week to 6 months long. And you only get a limited number of attempts at the placard in a period of time? After a certain amount of views of the placard, it just starts saying "Your eyes are hazy and cannot discern what is on the placard." (and won't show if it's buyable or not). And potentially make it so if you click the placard and get "You cannot discern what is on the placard." enough times within a certain timeframe (make it random though, both the amounts of times and the timeframe), and that should stop it. Since instanced housing won't happen, as SE are being too stubborn about the wards.