The Collaborative International Dictionary of English v.0.48:

Fault-finding \Fault"-find`ing\, n.
   The act of finding fault or blaming; -- used derogatively.
   Also Adj.
   [1913 Webster]

WordNet (r) 3.0 (2006):

faultfinding
    adj 1: tending to make moral judgments or judgments based on
           personal opinions; "a counselor tries not to be
           faultfinding"
    2: tending to find and call attention to faults; "a captious
       pedant"; "an excessively demanding and faultfinding tutor"
       [syn: captious, faultfinding]
    n 1: persistent petty and unjustified criticism [syn:
         faultfinding, carping]

Moby Thesaurus II by Grady Ward, 1.0:

20 Moby Thesaurus words for "fault-finding":
   captious, captiousness, carping, cavilling, censorious, censure,
   contentious, critical, criticism, fussiness, fussy, hair-splitting,
   hypercritical, hypercriticism, niggling, nit-picking, pettifogging,
   picky, querulous, quibbling



Moby Thesaurus II by Grady Ward, 1.0:

130 Moby Thesaurus words for "faultfinding":
   Jeremianic, adverse criticism, animadversion, aspersion,
   bad notices, bad press, beef, beefing, bellyache, bellyaching,
   bitch, bitching, captious, captiousness, carping, cavil, caviling,
   censoriousness, complaining, complaint, complaintful, crabbing,
   crabby, cranky, critical, criticism, croaking, cynical,
   destructive criticism, disappointed, discontented, disgruntled,
   displeased, dissatisfied, dissent, envious, exception, flak,
   fretful, grievance, gripe, griping, groan, groaning, grouchy,
   grouse, grousing, growling, grumbling, hairsplitting, hit, holler,
   home thrust, hostile criticism, howl, howling, hypercritical,
   hypercriticalness, hypercriticism, imputation, kick, kicking,
   knock, lamentive, malcontent, malcontented, moanful, mournful,
   murmuring, muttering, nagging, niggle, niggling, nit, nit-picking,
   obloquy, out of humor, overcritical, overcriticalness, peeve,
   peevish, peevishness, pestering, pet peeve, pettifogging,
   petulance, petulant, plaintive, plangent, priggishness, protest,
   puling, querulant, querulous, querulousness, quibble, quibbling,
   rap, rebellious, reflection, reproachfulness, resentful, restive,
   restless, scolding, slam, sniping, sorrowful, squawk, squawking,
   stricture, sulky, swipe, taking exception, trichoschistic,
   trichoschistism, ultracritical, ululant, unaccepting,
   unaccommodating, uneasy, unfulfilled, ungratified, unhappy,
   unsatisfied, wailful, whimpering, whining, whiny, yapping