There's an interesting piece in the Guardian today asking photographers for their worst or failed photographs.
Here's Jillian Edelstein's 'worst shot' (it's of Gregory Peck, which doesn't actually seem to matter):
Is this a failure? I think if I took it I'd die a happy man. Technically it's perfect: the lighting is stunning, the angle interesting. Artistically, it says so much about age and about portraiture. Peck's expression and eyes seem to be challenging the viewer: there's only him to look at and he's staring back at you with a smirk that mocks your interest.
Every single one of my photographs are worse than this 'worst shot'.