● Polyester polyol quality should be judged by data rather than product name alone. ● Hydroxyl value, acid value, water content, and molecular weight distribution are key indicators. ● Abnormal data can affect reaction control, processing stability, and final product consistency. ● Routine COA values are useful, but deeper testing may still be needed in demanding applications. ● Better material selection comes from matching polyester polyol data to actual end-use requirements.