For a contrary opinion, I've sold a few small-value items through Scarce.city, worked directly with Chris, and had a good experience.
The criticism about reserve bidding, and sellers backing out, is very legitimate. Oftentimes over the years I've had sold something at auction that went for much less than I expected, but those are the rules, and the item gets to the buyer regardless. But in this situation, I'd blame the seller more than the auction house. Taking all items in first for inspection, as an alternative, would increase their overhead greatly. The liability alone of keeping things secure while in escrow would be very challenging. Maybe this is something they can do as they grow, or figure out better guarantees for both parties in the meantime.
I just see people coming in and throwing shade at their whole operation from various angles, and just wanted everyone to take a step back and see that scarce is doing something interesting and unique, and giving exposure to bitcoin and collectibles in an industry where just staying afloat in the last few years has been a struggle.