Why not "I look in the mirror"? Would that be something quite different/nonsensical in Polish?
I look at = patrzę na (+accusative)
I look in the mirror= Patrzę w lustro ( accusative) , do lustra (Genitive) (I have no Idea if those two have a difference, one is regional or sth, I'll try checking )
I remember from childhood zwierciadło as mirror and lustra as chandelier... was that some kind of dialect?
"zwierciadło" as a mirror - yes, it's more... poetic, but correct. Added.
"lustra" (in plural?) as a chandelier - that's pretty surprising, I don't think it works. "chandelier" is "żyrandol".
люстра is the Russian and Ukrainian word for chandelier - it could be that the people I heard speaking Polish mixed the two languages. (which would also explain why they said zwierciadło - since it is more like the Russian word for mirror.