This is true of most companies reviews. If they are reasonably small enough (say under 500 to 1000 employees), they all have the same pattern (chronologically): Sparse to no reviews for a while. One or two negative reviews. A few days to weeks later... a huge influx of positive reviews for a few days. Then back to nothing.

I've seen this happen at a previous place I worked at too. One extremely on-point and constructive review with low stars and tons of likes that was then followed by a flood of junk 5 star reviews that obviously the CEO or his lieutenants wrote. There doesn't seem to be any way to combat those fake reviews now.

At job before last, we were offered a large bar of Cadbury's chocolate (a 200g Dairy Milk if I remember correctly) as a sweetener (hoho) for writing a Glassdoor review. Which would be written and emailed to the person who came up with the wheeze and...

anyway, afaik all those chocolate bars are still in a cupboard somewhere at the offices

I've seen the exact same thing as a small-mediumish (100-200 now) start-up I used to work for, there'd be an email sent around to encourage employees to leave a good review, seeing as you can't change your review after it's a scary way to waste your shot.

But I guess that shots wasted anyways if the system is rigged to begin with.

I generally don't bad-mouth previous employers, as it risks limiting your career. However, the only review I ever left on Glassdoor was of the most toxic software job I ever had. The company basically had nothing but dozens of 1 and 2 star reviews. A few months later I checked again and there were about 10 brand new vague 5-star reviews that were all submitted within a day of each other. One of them even said right in the review something like "boss told us all to write 5 star reviews, so here's mine: This place is horrible."

Just checked the company again, and my review has since been removed (but some other 1 star reviews are still there).