"You can't just show a snippet that makes it seem worse than it is," said Rozelle, the Stetson University professor.
When the accused admit to posting the materials themselves, authentication isn't as much of a question. But in the cases of Godbehere, in Hawaii, and Cox-Brown, in Oregon, the incriminating posts put them in the awkward position of having to disavow their own words, experts say.
Either way, Rozelle says, criminals' trumpeting their crimes is nothing new.
"People have always said foolish things," Rozelle said, "but now they have the ability to say it louder and to more people."