I think y’all pretty much hit the nail on the head on whether or not one should buy new/used radios. Used will always be hit or miss especially if you are not 100% familiar with how some manufacturers handle model numbers cough Motorola cough. Buying used can also be an issue if buying from those who really don’t have a way to test a radio. As was said, “it makes power” doesn’t always mean the radio can receive. “It powers on” doesn’t always mean it can transmit. “It works fine” also doesn’t mean the serial interface isn’t burnt out on it either (for reprogramming). In those instances, the “included” programming services and requesting a full printout regarding the performance of the radio are vital with used.
Factory refurbished is a great budget friendly solution though. Tested for proper function by the manufacturer, often re-cased, aligned and with a warranty. Least amount of risk for a second hand radio.