A defamatory statement must be false -- otherwise it's not considered damaging. Even terribly mean or disparaging things are not defamatory if the shoe fits. Most opinions don't count as defamation because they can't be proved to be objectively false.

Is defamation always untrue?

The term 'defamation' describes an untrue statement that's been presented as fact and causes harm to the character of the person it describes. If someone's reputation is damaged because of a false statement, this statement will be considered defamatory.

What if a defamatory statement is true?

In most states, truth is a complete defense to a libel action. You generally can't sue if the statement in question is true, no matter how unpleasant the statement or the results of its publication. ... A public figure, someone like Madonna, may succeed on a libel claim only by proving actual malice.