How do you know if something has good fats in it rather than bad fats?

Natural vs Processed: If the fat is of natural origin (; not concentrated from plant sources; we are animals, not plants) then probably healthy. E.G. Fats on/in meat, lard, bacon grease, also palm, coconut ; olive oil (if high quality). If concentrated from plant sources or processed/hydrogenated (even without trans-fats: only cis-fats) then highly questionable: ie paleo principles ; consistent with all actual science.