I literally just got off the phone with a USPS customer service rep yesterday when I first saw this thread, impeccable timing. I read some of the posts and was going to share, but had to keep moving. Usually, we have little to no problems with the USPS, but it must've been my turn to get bit.
I ordered a poster for my game room weeks ago, and the seller sent it via their Tacoma, WA USPS. The item was shown as picked up but soon after went into the 'In-Transit, Arriving Late' notes in the tracking. I called the USPS to make a claim, but a day or two later my local manager called and said he's got nothing, had to close the claim and that it should be dealt with at the Tacoma branch, which I thought was weird. Apparently the service rep made the wrong location designation in the claim I later found out in this second call. 7 days or more went by, well after the expected delivery date, and it stayed as 'Arriving Late' for a few days until it then reverted back to 'Pre-shipment, waiting for item'. The seller promises they sent it out.
Then, the seller feels bad about the situation and opts to send another poster to make up for the USPS blunder, and that one was supposed to deliver yesterday, but went into the 'In-Transit, Arriving Late' notes and removed the delivery date. This is why I called back and had them review the claim another time.
Fortunately/Unfortunately, my poster arrived today. It's been through the ringer and has irreversible creases and bends in the paper. Damn.