Small but inquisitive jurors poked and prodded, questions and discussed the subject. Bruised reputation, damaged pride, spite, jealousy all the anger and hurt people experience when something untrue is discovered online or off. The motivation to defame, accidentally or with intent goes on but to take action in law seems to come down to being able to prove loss of income as a result of the defamation. 

The distinction of interest is between libel and slander. Libel being written and slander being verbal. Saying stuff on Twitter essentially counts as written. Retweeting is considered accessory. Anecdotal revelations of experiences in order to remain anonymous can get you in to trouble. Commenting anonymously may not protect you either.