Sounds a tad extreme, Anna.

His vapeshop friend may be honest and reputable, too. I believe
assaultshaker somehow spilled some water over the top of the cell, which can remain there inadvertently as it is sort of a cavity and end up causing those corrosion specks. Of course these are all presumptions, like yours. I'm biased too, as I've seen insane levels of performance harmless rust covering (because of the effects of the aforementioned soldering flux).
I wouldn't mind having a conversation with the store owner if I were to find such a thing appropiate. If you're intentions are good and you're nice and respectful there's really nothing to worry, because in such a case if the owner gets disturbed and/or ...... with you this is an indication that ending up such a relationship is for your own good.
Cheers everyone [emoji14]
P.S.: properly focused pictures are of great help in discerning details,
assaultshaker. I sometimes take great deals of effort to obtain proper pictures, and it pays off.