Places that give you a means of communication, but then ignore you when you use it. Spent the last few nights in a hotel in Georgia. The first day my room didn't get serviced. (I don't care if beds get made but I needed trash emptied and TP restocked). Called the front desk, they promised that it would be serviced the next day if I hung the placard on the side that said "Please Service" (and the reverse side said Do Not Disturb). Found the placard, hung it as instructed. Next day, no service. Called front desk, they said sorry, be sure to use the placard. I again said I did. Last day, I slept in before my flight, checked out around ~9:30 and ran into the cleaners buzzing around the hall. I asked why my room didn't get serviced according to the placard on the door. She says "oh we don't go by what the tag says, people don't realize they say different things on each side so they just hang a tag to mean Do Not Disturb so if we see a tag at all we skip that room".
If the tag has different instructions on each side, then you should follow what the tag says. Or tell the front desk to quit instructing people to use the thing. If you're treating the tag to only mean Do Not Disturb, then throw those tags away and just give us tags that only say DND. Ugh.