I have seen more of these Paid Posting groups pop up over the past 2 months that I can count. Now I will not name any names today, but it seems that in every case I have taken time to investigate there is a total lack of professionalism and/or the company is just illegitimate and offering a phony service. The “testimonials” I have read are often only one or two in number and don’t offer a URL to visit and check things out. I have looked at a dozen or more paid posting companies and this is almost always the case. Also, when I actually find some folks giving honest reviews and showing the actual posts the company made, it never is very positive. The best rating I have seen in an in depth review was a B rating.
I have also noticed that several of the companies I looked in to in October are no longer around in December. Many of them make a great sales pitch about the quality writers and having to hire new writers due to the vast number of orders and on and on they go. Until I see a solid company with a trend lasting longer than 3 cutomers, I will not be recommending this to anyone. 
If you follow sitepoint’s marketplace as I do, you would have seen a couple of those operations being sold.