I tried to buy a used cellphone today at the mall.
There's a shop in the local mall that buys and sells cellphones. The shop had an ASUS ZenFone V for a tolerable price. I bought it, and immediately headed to the Verizon shop at the mall, because I needed a SIM with NFC (because VZW still has separate SKUs for this).
Guy offered to swap the SIM and activate the phone for me.
... and promptly discovered the phone on a non-payment suspend from the previous user.
Crap. Had to return the phone.