they are probably all straight backed the pics of dogs with sloped backs are stood or stacked that way on purpose. Left to stand square, all four feet under their body like they picture shown will have straight backs. The same dog can be stood in many different poses to make it look different. Great looking dogs can look awful in some pics, as can people. Sloped backs will have 1 rear leg back and the other bent and forward right under the dog, almost the splits in the rear, so if they stood like that and had a straight back think how weird they would look relaxed.