Keep in mind I live in Canada, so my knowledge of the law might be slightly different than what is actually the case in the US
The evidence that the police found is in fact valid, because you opened the door. By opening the door, you are consenting to them entering your house (or hotel suite) and you are liable for anything they find in plain sight. They are not allowed to open locked stuff, or go tearing through sofa cushions without a warrant. However it is completely in their limits to request entry to a house, and if entry is given they may walk around and if they see anything it's fair game.
Barring that, if you can prove that you had no idea the coke was in there, that you hadn't been in that room, etc, then you're safe. You should not be held accountable for the actions of others. However, if you have priors, if they found your jacket in the room that had the coke in it, or if there is any other evidence or history that might suggest that the coke might be yours, or you may have been involved with it being there, you may be in some trouble.