I worked as an intern at the Tokyo property. Plus, I learned a bit about this stuff in school.

Usually, most hotels turn beds quarterly, where the comforters and the blankets are changed. But, some hotels like to neglect this, and they only do it twice a year. I doubt if this is any different with the super luxury hotels.

Don't even bother asking the front desk to have your comforter changed. They have already scheduled when to do it, unless there's a major problem with a particular comforter that requires immediate attention.

As for paranoia, make sure that your body parts are always in contact with the SHEETS. Unless the hotel has comforters/blankets that use comforter/blanket covers (so they can launder the covers daily), then chances are that they're not clean.

While I'm on this housekeeping topic, I should add that the coffee makers are probably dirty as h*ll too. Wash it if you absolutely have to use it.

Hope this helped.