For those wondering why allowing paid editing might not be such a good idea, take a look at this:
http://en.wikipedia.org/wiki/Talk:Almeda_University#Paying_freelancers_to_re...
It's a long-term contract for a 7-days-a-week effort to replace negative edits with positive ones. Full marks to [[User:Randywombat]] for finding this.
Note in particular the endless self-justification in the Almeda approach. I think that will undermine any attempt to find clever rules that allow paid editing where there is even the slightest possibility of conflict of interest. I'm sure any of us could rewrite that job description to make full use of Wikipedia jargon. And if somebody's income depends on them not getting the essential meaning behind our words, they may be able to keep it up for quite a while.
William