The Collaborative International Dictionary of English v.0.48:
Fault-finder \Fault"-find`er\, n. One who makes a practice of discovering others' faults and censuring them; a scold. [1913 Webster]WordNet (r) 3.0 (2006):
faultfinder n 1: someone who is critical of the motives of others [syn: cynic, faultfinder]