I've had the room not be available in Paris, the Hague, and Amsterdam, although there would have been a room if I had been willing to give up my suite.

Boutique hotels in Paris might not permit access before noon; that seems to be the tradition.

In Italy, I've seen local chain hotels (four star range) play the game that no rooms are available until they all magically become ready at exactly the stated check in time, typically 3 pm. Needless to say, I will never ever go back to any hotel that does this.