A photo explaining how why Fitted Sheets are needed In Hotel Rooms.
Here is a Photo showing how you can wake sleeping on the mattress, and for sure a fitted sheet is best for sex.
Solution: Carry safety pins and pin each of the corners, and one in the middle of each side.
Without a fitted sheet you can wake up on the mattress.
Is the room really good, check the bed under the sheets, and take off the pillowcases.