Here is what I recommend:
Have them TEXT you when the room is ready. You can sign up for this at your online check in. Then when you get the text (whether you are still at the airport or already on your way to MK), check the room location/view on TouringPlans (where they have the interactive hotel maps). If you have an obvious issue with the assigned room (for example: facing smoking courtyard - yes, this will sift into your room and if you have bad allergies, you cannot stand that!... or upstairs while you need downstairs for medical reasons, ...) Call them right then and there.
Don't wait until after midnight, if this is so important to you.
It might take 30 minutes to sort it out, but you'll be glad to have the peace of mind to know where you are going after your Halloween Party!
In general, rooms that are in an area that never gets a breeze, or are never exposed to natural light/the sun, and have faulty AC units, may get mildew issues at any hotel in the world. As far as smoking... guests are not allowed to smoke in the rooms. So I would think that these rooms others have encountered, either had guests smoking illegally inside the room, or guests smoking in the "open doorway" (yes, that will still get into the room), or the room is facing one of the too many "smoking courtyards": when the maids are cleaning they leave the door open for longer and - tadaa- smoke can find its way into your room and clings to the fabrics.