Low/bad/lowest quality, Blurry/out of focus,
Watermark, 
Bad anatomy/poorly drawn/disfigured/deformed,
Mutated/extra/missing limbs/malformed hands/fingers,
Long neck/body,
Kitsch/childish/old,
Incomplete/cut off,
Duplicate/copy/two faces,
Out of frame/distracting background,
Heterochromia (oddly colored eyes),
Dots/pixels.