Here's what I learned from friends in industry that "make things". During launches for new products that are considered niche, there are often buys that get returned for a bunch of non-damage related issues. In this case, I am assuming it had to do with HDMI handshake problems that were discussed in many forums. Because I don't have elaborate setup requirements, I took a chance and saved some cash. Electronics fail within the first year if at all and I got it direct from Marantz so their 1 year warranty was fine. So for ME, the savings were worth it. If you're asking about a product that hasn't been reported to have "issues" (read-user error or user expectations), I'd probably not do it because whatever went wrong, might have been via damage. My $.02.
EDIT: I should mention that my refurb didn't come with ANY of the original packaging. It had all the "stuff" but came in a plain single double-wall box without any of the "normal" experience type stuff you'd get buying new. (Styrofoam, silk covers etc.) But what I got is over $1000 off a product that I have enjoed DAILY for well over a year.
