this is an interesting point, I was more thinking along the line of digital goods like:

- mobile phone applications: storefront (app store, google play) review are well known to be manipulated, and whatever is done to control the issue is clearly loosing. - video games: Steam is also well known to be a battleground for so-called review bombing and counter review bombing. Although Steam is very good at providing data to understand the context of the review, it clearly caters to a specific audience.

Glassdoor is more egregious because of the anonymity it tries to provide for the reviewers and how authenticity and veracity o statement would be very difficult to assess.