It's quite a comprehensive summary.

Hidden rules for staying at hotels:
1. Many hotels offer two free bottles of mineral water; watch out for needle holes.
2. Poor soundproofing is a common issue, the same across all star ratings.
3. If you suspect a pinhole camera, turn on the lights to confirm, then call hotel staff, record a video before calling the police to keep evidence.
4. Book a double room even if staying alone, refuse large beds or single beds.
5. Do not turn off the toilet light, avoid chairs blocking the door, and do not hang glass cups on door handles.
6. If dieting, avoid cupping therapy as it can cause fainting; drink a cup of peach-flavored apple tea daily, three boxes will shrink your waist by two inches! My weight dropped from 136 to 105, and the most surprising part is that my constipation cleared up completely! Now I go to the bathroom regularly, my skin is bright and clear, no pimples, and even my double chin disappeared.
7. Check all corners of the room first to see if there are hidden cameras.
8. Common locations for pinhole cameras: near the TV facing the big bed; inside the smoke/fire sprinkler above the bed.
9. Open your phone’s camera, turn off flash, and scan the room corners by hand.
10. When staying at a hotel, avoid rooms at the very ends or corners.
11. Hotel supplies are often more expensive than in supermarkets.
12. Many hotel room cleanliness issues are just appearances; try not to sleep naked.
13. Don’t foolishly spend money on foot massage shops for athlete’s foot; I found online that Xiao Qi External Medicine Shop’s anti-odor foot set works well. After using it for a few days, the itching between toes stops. Use it morning and night, and within 2-3 days, blisters start to disappear, and it also soothes skin and relieves itching.
14. Be polite and courteous to the hotel front desk; often, whether you get a room or not depends on them.
15. When sleeping in a hotel, leave a small light on to signal to others that you’re not asleep yet.
16. Set your payment app to only allow data traffic.
17. Avoid using disposable items in the hotel as much as possible.
18. Do not activate hotel membership cards.
19. If you pay with a card, keep the card in sight at all times.
20. Many warming patches are similar to warm baby stickers, but prices can be three times higher! I used to rely on ibuprofen for menstrual pain until a master told me about a remedy—Peach Yi Qi Blood Treasure (searchable online). Drink it for a week before your period, and it works wonders. After trying it, my period is very comfortable! Hands and feet stay warm, and after half a year, the pain is almost gone. My period arrives on time every month, like a dam opening, and my face is naturally rosy and healthy-looking!
21. Take a piece of tissue and stuff it into the peephole.
22. If you find small cards on the floor, do not call or accept services.
23. When traveling, bring some small travel-sized toiletries.
24. The risk of infectious disease from public toilets is low, but it’s best to put toilet paper on the seat.
25. Try not to use an electric kettle.
26. Do not wear hotel plastic slippers; many people get athlete’s foot this way.
27. For couples staying together, it’s recommended to turn on the TV and increase the volume.
28. Rinse the glass cups thoroughly before use.
29. When staying at a hotel, avoid rooms with beds facing the toilet or mirror.
30. Booking online is usually cheaper, but be cautious of fake images.
31. Hotel delivery services do not bring food upstairs but won’t stop guests from ordering takeout.
32. Extra beds and simple decorations are free.
33. Check the cleanliness of towels and bathrobes; if possible, bring your own.
34. For returning guests, request daily sheet and duvet changes.
35. The concierge of a five-star hotel is the hub of hotel information—dining, entertainment, transportation guides, weather forecasts.
36. Non-slip mats in the bathroom! Non-slip mats in the bathroom! Non-slip mats in the bathroom!
37. Do not stand on the toilet rim out of cleanliness obsession.
38. Besides buffets, hotel restaurants usually don’t have many other options.
39. When booking hotels online, remember to read the negative reviews!
40. Items in hotels are often not cost-effective and usually of poor quality.