I honestly don't go OTT with my requests on my reservations and I've always been lucky enough to have wonderful rooms assigned to me.
On the rare occasion that I have had a specific request - eg. I wanted concierge but no rooms were available, I faxed a request to the resort a few days before but made it clear that I would be willing to pay any additional costs incurred.
The way I see it, if you're not happy with your room you can complain. I have only had to do this once at Beach Club because the room I got was miniscule. When i called to complain I was told that I should accept it because I got a good room rate.
I politely said that a good room rate should not equal small s...hole that you couldn't swing a cat in, and that I spent thousands each year in WDW (on that particular trip alone I was staying 14 nights paying deluxe prices), and the room I got did not vaguely resemble those in their brochures. Only then did i get moved to a normal sized BC room. I'm sure they'd put me in CM accommodations.
There are not too many bad rooms, but if you do get one, don't be afraid to complain loudly, no matter what rate you got. Disney more than recoup the money you save on discounts through dining discounts, souvenirs, and park passes - and repeat visits.
Generally I've always found it best to go with the flow but I wouldn't hesitate to complain if I thought I was getting a bad deal.