This is what I presume is happening too. I have worked at several companies that received a lot of poor reviews and often what happens if you keep track of tho

This is what I presume is happening too. I have worked at several companies that received a lot of poor reviews and often what happens if you keep track of those reviews over several months is that they "mysteriously" disappear. Of course by that point the person who left the review has probably moved on to a new job and can't be bothered writing another review that is sufficiently vague as to avoid potential removal. One company I worked at even had its overall rating significantly messed with (over 0.5 change within a month), as those old reviews disappeared and "mysteriously" a bunch of vapid positive reviews appeared. All that said, I still check Glassdoor before every job I interview for. You just need to be mindful - especially for larger companies who can afford the time to curate their reviews - that the score is perhaps a little inflated, and that the reviews that remain are as tactfully-worded as possible to avoid deletion.