A defamatory statement is a f alse statemen t of fact that exposes a person to hatred, ridicule, or contempt, causes him to be shunned, or injures him in his business or trade. Statements that are merely offensive are not defamatory (e.g., a statement that Bill smells badly would not be sufficient (and would likely be an opinion anyway)). Courts generally examine the full context of a statement's publication when making this determination.

I n rare cases, a plaintiff can be “libel-proof”, meaning he or she has a reputation so tarnished that it couldn’t be brought any lower, even by the publication of false statements of fact.

http://www.dmlp.org/legal-guide/what-defamatory-statement