Sample images on theme

This might be a self-evident question..

What kind of images can designers use on their themes? I’m referring to images used in sample posts, or content sliders – image not sold with the theme. I’m currently testing a theme with default windows 9 pictures and they look really nice. I wouldn’t want to replace them..

I think this will answer your question.
Next to that, Envato has also created an asset library for their sellers.

Thank you!

themeforest is very prepared..