The difficulty (or otherwise) of proving defamation is not relevant. The potential cost of venting your spleen in the public domain IS.
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The late Justice Frederick ('Funnelweb') Myers of the Supreme Court of NSW was wont to muse that '"Most litigants aren't in my court looking for justice. They're there to get even."
Do you have $500k to throw away by saying that some body is, say, soliciting prostitutes on overnights?
Captain Adolphous Hippolyte Spriggs, employed by a certain Australian international airline, a man with multiple shady connections,
a self-confessed pimp, userer and person of dike-rat propensities, had on his 'books' so many professionals in so many cities, he'd boast that were the whole of the Foreign Legion queued up, they'd just have to wait their turn.