As far as B-stock goes, I wonder how much of these issues are due to human error. I think a lot of stuff slides through the QA process at a lot of companies and I've seen it first hand like for example where some kid will get bored or lazy after churning out repairs all day or functionality testing and its nearing time to go home or the weekend and obvious issues will be signed off on, considered 'good enough' or ignored.

It does feel like a lotto sometimes, no matter what company you decide to buy from. Personally I've never had good luck with b-stock items from any company but that's just probably my luck. I can't tell somebody how many times I've ordered b-stock items and it was super obvious that if somebody did a proper functionality test or used the item it shouldn't have been resold or passed an inspection.

Hopefully your next headphone is a good one!