One of the best things about Tate Modern’s Picasso exhibition is it contains some terrible art. I mean real howlers. Paintings in which we see the modern master fluffing his lines and losing his form. It’s such a relief. Not because we learn he is fallible like the rest of us – we’re not idiots, we know artists aren’t gods – but it shows the exhibition’s curators had the confidence and integrity to tell the whole story of Pablo Picasso in 1932 – his so-called annus mirabilis – and not palm us off with a superficial Now That’s What I Call Picasso ’32: Greatest Hits compilation.