Yes. But not how you imagine it. Generally they are just workers who have an interest an so they post and because the internet is full of a-holes they dont make their positions obvious.
But there are astro-turfers who are paid by marketing to spread news and info and build hype for things.
And then there's actual research studies where they invite various folks to join a forum and chit-chat as if it was a focus group but instead online and at their leisure.
Generally if you complain on a forum or even praise things, no one hears it other than the occasional reporter who wanders by and posts us on their 6pm news blurb. So if you post online and don't do in-park surveys but have things you don't like and want changed, it's your own darn fault.