Anecdotal evidence is one person's story or observation (e.g., "my dad has no bruises"). It's subjective, uncontrolled, and can't prove or disprove general effects.
Scientific evidence comes from large, controlled studies tracking rates across many people while accounting for variables like age, dose, and other meds.
Aspirin inhibits platelet clumping, increasing easy bruising and bleeding risk. In 80-year-olds, thinner skin and fragile vessels amplify this. Trials (e.g., ASPREE) and medical data show higher bruising/hemorrhage rates on aspirin, though severity varies widely by individual factors. One person's lack of bruising is possible but doesn't negate the documented population-level increase.