A dog cannot digest boiled butter. (Hindustani) (That is:) A mean man cannot appreciate a confidential talk, but will divulge the most important secrets that are revealed to him.
A wise man associating with the vicious becomes an idiot; a dog travelling with good men becomes a rational being. (Arabian)
Of brothers-in-law and red dogs few are good. (Spanish)
They seated the dog in the palankin; on seeing filth it jumped down and ran after it. (Telugu - India)
Scornful dogs eat dirty pudding.(Scotch)
He blushes like a black dog. (English)
Even the street dog has his lucky days. (Japanese)
-- from Curiosities in proverbs: a collection of unusual adages, maxims, aphorisms, phrases and other popular dicta from many lands, Dwight Edwards Marvin, ed. (New York and London: G.P. Putman's sons, 1916).