I've never seen a PC or lappy that had "upside-down" USB ports - seems so counterintuitive it's hard to believe any mfr. would do it (oh, hello Dell).
I'd always proffer the plug with the side where the holes don't have the contact-plate right behind them, and the join in the metal isn't (where there is a join, which is pretty normal), as the top side. Never been an issue IME.
Apart from the rise of micro-micro-thumbdrives which only have the contact-plate and no housing. Made a litany of fumbles with those bleeders :(
And then there're the PCs that put the USB sockets sideways (oh, hello again, Dell, but plenty others too). I can't imagine there's any orthodoxy within that.
Still, you know, I guess it's better than what we had before. Mostly.