One product (power bricks for MacBooks) had over 1000 5 stars, then the 1 star reviews came in where people actually had their power adapters catch on fire. Amazon, or maybe the seller, shut the review/product down. Now, it's back:
https://www.amazon.com/KUPPET-MacBook-17inch-Compatible-MacB...
Lots of verified purchases. All the reviews are within the same date range. It doesn't take machine learning or advanced AI to catch this; a simple SQL statement should be enough to flag these. But still, they persist.