The hotel's owner, Kyrk Pyros, had decided to leave the room untouched in case the crew ever had to come back for re-shoots, although you would think that after two freaking years, he would have at least had someone run a Dustbuster through it. Presumably for Mr. Kyros, that leftover movie set was the equivalent of a tender kiss on the cheek from Haim that he vowed he'd never wash off.
To be fair to the investigators, the George Washington Hotel doesn't have the best of reputations to begin with, considering the 12 deaths that have occurred on its premises since 1923 and the local rumors of it being haunted. Then there was the fire. So, all in all, the gruesome discovery of a murder scene would actually be pretty standard for the George Washington Hotel.
This is essentially their equivalent to a continental breakfast.