the key is to get it while its fresh with really cold water.which i can never do.
i always use fingernail polish remover before a wash and wax.
only time its left marks was on my black truck and the sap had been there for months baking in the sun. the sap left a mark itself in the paint and i left little web scratches around it from rubbing so hard.
but thats on black and a good wax job hides it good.