I wrote about my bad experience at one of the company I interned for. Some PR from the company comment on my review, I knew the PR guy cuz he goes around doing it to other reviews there and create fake reviews.
Anyway, I call him out on it said he's using ad hominem for one of his tactic in the comment. Other users comment and back my report up.
After a few week glassdoor deleted my comment and the comments that back me up, they left the PR guy comment up. I wish I could have screen shot it.
Eventually they did away with the comment system.
I don't trust them at all.
There are aggregate surveys from O'Reily and stackoverflow. I think it's pretty decent. O'Reily doesn't give raw data for their data science survey so I couldn't do any survey analysis to confirm it but they release their linear regression model.