It is a loss of soap to wash the ass’s head.
More Spanish Proverbs:
The stew mixed by many is ill-seasoned and worse cooked.Spanish
The bread never falls but on its buttered side.
Spanish
Silly sheep, where one goes, all go.
Spanish
True love suffers no concealment.
Spanish
Giving alms never lessens the purse.
Spanish
I thought I had made the sign of the cross -- and I hurt my eye.
Spanish