nastiness

noun

A desire to harm others or to see others suffer: despitefulness, ill will, malevolence, malice, maliciousness, malignancy, malignity, meanness, poisonousness, spite, spitefulness, venomousness, viciousness. See attitude/good attitude/bad attitude/neutral attitude.

The noun has 3 meanings:

Meaning #1: a state characterized by foul or disgusting dirt and refuse
  Synonyms: filth, filthiness, foulness

Meaning #2: malevolence by virtue of being malicious or spiteful or nasty
  Synonyms: cattiness, bitchiness, spite, spitefulness

Meaning #3: the quality of being unpleasant
  Antonym: niceness (meaning #2)