Honest answer, I have no interest in doing that research. I wouldn't know how to make that determination with any degree of confidence. Even if I could, I feel like it would require that I constantly monitor how a site delivers its ads.
Fortunately, I am at a point in my life that if I really like something, and they offer an ad-free subscription, I can support them that way.
I started blocking ads when ad networks failed to properly vet their ads and allowed malicious ads to be distributed.