F for Fake ending explained

What happens

Welles ends by admitting that the long Picasso story, told with such convincing detail, was invented, and that his promised hour of truth ran out long before. You realise you believed it. The film has been making a fake all along.

The last image

The film closes on the admission itself: Welles, the showman, owning up to the trick he has just played on you.

What it says

A fake that announces itself is more honest than one that hides. Welles shows how easily a good story creates belief, then hands that lesson to you. He ends on the trick because trust is the subject, and an honest liar may be the only kind worth trusting.