I'll rephrase my original comment slightly. MF is not supposed to/does not intentionally sell returned merchandise as new. That is the whole reason the 'open box' designation exists in the first place.I and lots of others on here have definitely received returned merchandise that was sold as new from both GC and MF. However, SDOTD is probably mostly overstock and therefore new.
As for D’Angelico specifically, this is likely a manufacturer strategy. I see lots of retailers advertising them as their BF specials. It’s unlikely that all these retailers bought too many.
There have been two instances that I know of where there have been issues. Several years ago when they did their warehouse move, a lot got screwed up, including people receiving returns as new. More recently, people have apparently been getting items shipped from GC stores, which may as well be returns, even if they are technically new.
As far as D'Angelico goes, I think some people just need to find conspiracies. They hoped they would sell at full price, that didn't happen, now they're blowing them out to get what they can out of them. Not just MF SDotD, other retailers are doing similar to get rid of them.