One question per sample note
Instead of calling a sample simply good or bad, give it one question: Can the small text be read? Does the edge need another review? Is the contrast visible in this light? A narrow question makes the observation reusable.
Write down what the sample does not answer as well. A single sample is not a material guarantee, and a photo is not a substitute for a controlled validation plan.
Compare like with like
Keep the material name, observation date, and lighting note beside the sample image. Review the latest /updates/ entries for additional methods that keep early observations separate from final claims.