I'd sooner die than have him attend me." "Would you ?" said Olga.

"But why?
He's very clever." "That's just it.

He's too clever to have any imagination.

He would be quite unscrupulous, quite merciless, and utterly without sympathy.

Can't you picture him making you endure any amount of torture just to enable him to say he had cured you?
Oh yes, he's diabolically clever, but he is cruel too.