The character of the artist doesn't enter into the nature of the art. Eliot said that art is the escape from personality, which I think is right. We know that Velรกzquez embezzled money from the Spanish court and wanted power and so on, but you can't see this in his art.
Lucian FreudThe painting is always done very much with [the model's] co-operation. The problem with painting a nude, of course, is that it deepens the transaction. You can scrap a painting of someone's face and it imperils the sitter's self-esteem less than scrapping a painting of the whole naked body.
Lucian Freud