I tried to purchase products from Mercari several months ago, out of 4 purchases only one was the right item, one was the wrong item and two orders simply died due to their failure to communicate or ship, so I cancelled after 2 weeks.
My current order is about to be canceled for the same reasons, failure to communicate or ship.
Great News, PayPal is aware of Mercari's practices and gave me an immediate refund. Obviously too many refunds to Mercari buyers, due to fail to ship or to ship the right products.
Made the mistake of thinking they got better. Now way.
I am now waiting for an item to ship, that has not yet shipped yet should have been delivered, according to Mercari, 4 days ago.
So the sellers, fail to communicate, ship the wrong parts, fail to ship or ship promptly.
Then Mercari, blocks you from leaving feedback unless the sale completes.
So they all have unreal and unearned very positive feedback provided by Mercari, regardless of how terrible they are.