it might not have been a lie… e…g perhaps, another customer has asked to see the unit… and had open the box for that reason - so it wasn’t a returned unit, or even a demo.
(I’ve see this in various stores… where they can’t have all models on display etc)
I do get the frustration though… the main ‘issue’ with an opened box, is you cannot know the reason for it… you dont know if its a demo, return units, etc.
but, its tricky for local retailers too…
as @plragde mentioned customers can these days return things for no reason, they can just test it… etc … and most customers won’t ‘accept’ restocking fees or such like.
its ok, for big companies like thomann, they can afford to take a hit on their margins, but not so much for local retailers.