Is it always that smell wet mattress?

We have decided to painting our guest room over the weekend and go for a ride yesterday afternoon, a sort of get the paint smell from the nose, so to speak. It was an unexpected rain storm and wet as a result of the guest bed mattress that sat on the balcony. The majority of the mattress is dry because of the balcony tents, but on which side they stood was quite wet. I brought it in today and