Having a reliable source that you trust certainly goes a long way. Not fool proof, but I'd say good enough. Still good idea not to consider it a source of absolute truth and to continue to think critically.
Otherwise, eye witnesses will be crucial. "Pics or it didn't happen" is a relic of a bygone age.
Hell, you can manipulate what people see with their own eyes.
What I meant was that any recorded evidence will be tough to take on face value. One thing is manipulating, other is manufacturing with striking accuracy. While there are still signs, it's much more subtle now.