You guys have to remenber that if you buy a radio like the Z2 and is nothing wrong with it, you decide to returned to the store because you need money at the moment or couldn't really buy it because you max your credit card etc. Most of the people says the unit is damage, is freezing etc etc so they can have their money back faster. most of this unit goes to Pioneer to be checked and QC once again, they don't find anything wrong with it after testing it, they can't sell it as new by law so they label them refurbished. I work on a company that does the same steps when we receive "damage items" and we don't only test them by just powering and looking at it. We open the product and test the internal boards with special fixtures that tells us wich resistor, diode, chip etc. is damage, and if we find something wrong we change the complete PCB board and do hard test to it. This goes to radios too.
Just make sure to buy REFURBISHED ITEMS refurbished by the Original Company and not other companies. Companies like Pioneer pays $10,000 for a fixture that test let's say amplifier boards, and they pay much more for more complex PCB boards. other companies doesn't have that equipment they just check the items manually .