[bduerst]

It's the celestial teapot.

You can't prove it's existence, but you can't disprove it either. Belief in it's existence is purely based on opinion, not fact.

[scott_s]

"I like pizza" is an opinion. "I can read your thoughts" is a factual claim. We can test factual claims.

[bduerst]

Sure, and "I can hear the ghosts around me" is not, and it's a waste of time for anyone trying to prove or disprove this opinion.

[scott_s]

Which is fine, but often the claim is "The thing in this picture is a ghost." That's easily testable.