Something that happened to me. I left a 1-star review for a merchant that took 3 months to ship and it stayed up. I left a 1 star review for a completely unresponsive merchant that took Amazon a month to FBA for some reason (stock/non-commingled?) and it was removed with the reason "fulfilled by Amazon, we take responsibility for this experience", but Amazon did credit me back while the seller continued to ignore contact.

I've had sellers also threaten me over reviews while they ship counterfeit product, but that's a whole other can of worms