J'aime bien cette liste de site de banques d'image à éviter.

Du coup, j'ai fait un bookmarklet pour compléter ma requête quand je fais une recherche Google image.
C'est pas très beau (ianac - I am not a coder), c'est peut-être pas pérenne, mais ça me servira:

javascript:(function(){valeurorigine=document.getElementById('lst-ib').value;ajout="%20-site:istockphoto.com%20-site:123rf.com%20-site:dreamstime.com%20-site:reflexstock.com%20-site:photospin.com%20-site:crestock.com%20-site:canstockphoto.com%20-site:visualphotos.com%20-site:superstock.com%20-site:depositphotos.com%20-site:shutterstock.com%20-site:istockphoto.com%20-site:fotolia.com%20-site:agefotostock.com%20-site:profimedia.com%20-site:clipartof.com%20-site:colourbox.com%20-site:pixmac.com%20-site:inmagine.com%20-site:cutcaster.com%20-site:oneinhundred.com%20-site:clipartoday.com%20-site:gettyimages.*%20-site:yaymicro.com%20-site:graphicleftovers.com%20-site:mostphotos.com%20-site:featurepics.com%20-site:masterfile.com%20-site:vectorstock.com%20-site:bigstockphoto.com";nouvellevaleur=valeurorigine+ajout;document.getElementById('lst-ib').value=nouvellevaleur;document.getElementById('tsf').submit()})();