Please dont take this to offense its jus a opinion.
Plus Im very glad ur BP is good and healthy now.
But letting him soak in the same area u wash ur mouth, clean bacteria of ur hands n face that wouldnt be a ideal place to let him soak.
Just from the pics of wat is surrounding the sink "toothbrush, used ear swabs, hair." should be glad mites is all he has.
I wouldnt run off blaming the store right away in this instance.
Ur animal will reflect his or her environment even if u dont see the
things that can cause it harm.

But once again glad ur BP is doing good and hope u have many more years with it in good health...