I would agree with you there. I got a refurb 5s through Apple which only lasted a bit less than a year. I started having problems with the lightning port three months in and then it totally totally crapped out and the battery was starting to go. This could easily be explained by some substandard work on the port.
Apple says only the battery and outer shell are replaced, along with any defective modules. With a refurbished device, the Lightning port isn't replaced. So any wear and tear or slow ticking damage (e.g. liquid) from previous ownership will remain.