I thought this debate was about astroturfing - companies etc. faking grass roots support. Obviously that's wrong and where detected should be eliminated. Review sites are

vulnerable to this sort of thing but probably want to minimise it to retain credibility. Clearly even genuine grass roots reviews can't be entirely relied on. What else is there to say?

Yeah, TripAdvisor is supposed to be from people who like the business, they say it's fair, but now it seems like a lot of fake stuff. Too bad for some of Kunming businesses and now people looking for good restaurants get sent to hotels. How do they get all of the fake reviews?

you can pay people to post fake reviews.

I took a look at the Holiday Inn and Crowne Plaza and couldn't see any fake reviews - at first.

My Tripadvisor page is set to filter to English only.

All those fake reviews appear to be in Chinese.

Big companies are often at the top of the page for one of two reasons. They get more reviews, or they pay to be placed at the top of the page. The reviews are most likely to be genuine, as fake reviews carry reputational risk, as already pointed out.
Little businesses will often get friends, family and even staff to put in glowing reviews. In some cases this may just be in the beginning, just so that there are some reviews.

I think that online reviews can be the modern equivalent of 'buying a pig in a poke'. One thing my family always does is book one night initially, so we have somewhere to go when we arrive, then take it from there if we stay.

Another thing I do is look at the worst reviews only. Some of those are fake (from Mr Angry who just wants to punish the hotel for some perceived slight), but if you see things like, 'I couldn't sleep from the noise of the KTV bar', or 'Bed bugs', then maybe best to avoid those places.