The 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, Rolf Lauter, Jean Christophe Ammann, Craig Hartley, Museum für Moderne Kunst (Frankfurt am Main, Germany) (2001). “Lucian Freud: naked portraits : Werke der 40er bis 90er Jahre”, Hatje Cantz Publishers