Sentence:  I hope...that you are ignorant of the whole affair, and are so bold only because you are blind...And blind enough; so that you blunder on through thick and thin, bespattering all that come in your way, according to the old, laudable maxim, <WSD>'Throw dirt</WSD> enough, and some will stick.' 
Meaning of the word marked with <WSD> tags:  To make derogatory or malicious allegations, particularly about people in public life.