Share 'I need clarification on copyright, ethics, eye candy and googling.'

I understand the more direct issues about copyright, but what about public domain? Or What about magazine pictures--technically using advertisement pictures-is it OK. They paid that actor/actress/painter, furniture designer/dog/cat/bird/mouse a fee, so can you use it as part of a collage where you tear bits and then cover something? People have been doing it for years, is it OK? What about googl…