I have a spare fridge in the basement, so I put the leftovers there. But also, I don’t really like cold leftover pizza. So if I were staying at a hotel, I’d likely have no real use for it.
I’ve done that many times in the past, as have countless others. But apparently, it’s not a good idea.
Believe it or not, pizza can only be left out safely for two hours at room temperature. At higher temperatures, it’s safe to be left out for just one hour.
Anything outside of the temperature danger zone — which is between 41 to 135 degrees Fahrenheit (5 to 57 degrees Celsius) — is what you want to avoid,” advises Saleh. “According to the USDA, after two hours, you want to either heat the pizza back up or put it in the refrigerator to cool it down. So, say you’re putting pizza in the microwave or heating it up in the oven … As long as you get it out of that 135-degree F (57-degree C) range, then you should be OK.
Hidden Slight Hijack
I used to serve appitizers in a nightclub. The kitchen was buried deep in the bowels of this building and the walk was quite a way to the floor…
I was bringing a plate of Nachos out, and I noticed one lonely little chip, way off to the side of the plate… I grabbed it and scarfed it down, wanting to maintain the presentation of the dish 
I turned the corner to enter the room…
and there was a long string of cheese from the plate of Nachos up to my mouth! 
Nor here. But I have found that a toaster oven makes it great.
I’ve seen mentioned that one way to heat up pizza in a hotel is to use the iron.
I don’t like leftovers. Not home cooked food, not restaurant doggy bags. (Pad Thai is one notable exception - I’ll usually eat half my order and save the second half.)
I don’t want the people at the next table to speak to me. I certainly don’t want their leftovers.