Anyone who pays enough attention and perhaps knows a reasonable amount of people working in the parks knows enough to make educated guesses that they could pass off as "insider knowledge." There are of course posters who have a proven track record, but there's also many that pop up with no record. In my opinion, it makes sense to question them.
Correct me if I am wrong, but didn't the Marvel rumors come from people with proven track records? I fully understand questioning new people who claim to have inside information, but there are also people who try to discredit insiders that have a proven track record.