Seeing that it is a big and popular site, some of this must be going on. Not necessarily in the more elaborate form as you may find in the wiki entry and other definitions on the web but more in the sense of people pretending they are something they are not.
Eg, I remember not so long ago a link to a young man's blog which states that he works for a PR company representing a child care product that is in a v competitive and lucrative market and that the company reps like himself posted positive comments on the product when the opportunity strikes.
Another one I can think of off the top of my head is the Medela Mom Mavens scam where mothers are hired to big up Medela on parenting message boards whenever the opportunity lends itself. Politics imo is ripe for this sort of seeding of ideas. I have seen threads about infant feeding and weaning which have made me wonder if the poster is paid by a formula company too.
I see some threads on here and I wonder sometimes if the OP has an 'agenda'. But then again that may be the cynical and paranoid side of me showing.
Thoughts, anyone?