My pet peeve is the poor maintenance that is almost universal to hotel A/C's (both PTAC, split or central). Dusty, dirty vents and musty smelly units are the norm. I would be interested to know how many of these carry nasty things like legionaries etc. I challenge you to lift the front of a PTC (through the wall rectangular ones) and see the state of the dust filter. Sometimes it is caked in dust. I call maintenance every time I find one, just to remind them of what they should be doing....
My travel alarm clock also has a thermometer and it is almost a given that the set temperature on the thermometer and the temp on the alarm differ, and I have yet to see the thermometer read lower!

- Tim