Synonyms for Nastiness (same or very similar meaning)
WordNet sense 1 (a state characterized by foul or disgusting dirt and refuse):
filth, filthiness, foulnessWordNet sense 2 (malevolence by virtue of being malicious or spiteful or nasty):
cattiness, spite, spitefulness, bitchinessFrom the ODE community, based on WordNetadd/edit