Well, this is more complicated. Generally I do not want to overload participants with additional requirements, like posting in WOX only (well, that one sooner or later I have to consider still, I guess), either using some specific tag as "must". This will also return to me as boomerang while checking all entries not for plagiarism only, but for all those small details too, becomes too much time consuming.
And on other side, If we would really have big curators coming to visit those posts, which is not the case still