I’ve NEVER stayed at a hotel that was cleaner than my own home. I suggest that people use the card to write everything they found wrong with the room, slip the card into the envelope and hand it in to the front desk upon check-out.
Please make sure you post that on Yelp or Expedia - or even the hotel’s website.
I read those comments religiously and have found them to be dead on - for restaurants too. I never book anywhere without reading at least two sites for comments. Expedia always asks for readers’ comments.
When I’ve ignored the comments is when I’ve had trouble.
Each room should have UV goggles to detect cleanliness. That would be a little scary.
Find a few curly hairs around the toilet and bathtub drain? Place them in the envelope.