It depends on what you are doing with the editorial use image. Newspapers have stories with accompanying images on the same page as ads, so putting mixed content types in one place is not a problem.
If you are writing infomercial blog posts - in the style of a news or magazine story, but it's just a marketing/sales pitch - then stay away from editorial use only stock images.
Focus on the story the editorial use image is used with, not what else is on the same page or other parts of a blog, to decide if it's appropriate