GlassDoor has been gross about this for years.

Not sure if still the case but normally you have to not only 'sign in' but also feed them information (e.x. salary at a position, write a review, etc.) in order to be able to view much of anything.

They also do not give a shit about obvious 'juicing' (i.e. when it is obvious that upper management and/or HR is adding reviews where the 'con' reads like one of those softball warning phrases in a job description.)

This is the fate of every online review site. Every single one. Including IMDB as I realised yesterday while trying to find something to watch.

The most egregious example I've found was that the Danish postal service had something like a 4,8/5,0 rating on Trustpilot. You'll be hard pressed to find a more inept, corrupt and universally hated company. So in an attempt to improve their public image, they decided to game the ratings, instead of actually delivering mail properly.