The VIP cleaning is, as other posters have said, for those who have serious allergies. The room is given a special cleaning before you occupy it.
We had one done for my daughter and grandson's allergies at CBR in 2007. They did a good job of cleaning the room. There was only one problem. The cleaning agents they used were so strong that the smell of them in the room was overpowering.
So while those in our party with allergies benefitted from a very clean room, they were bothered by the strong disinfectant smell, as we all were.
This is one drawback to be aware of if you plan on requesting a VIP cleaning. Personally, I would take my chances and not get one, unless it were absolutely necessary. We stayed at POR two times after that, never requested a VIP cleaning, and didn't miss it, especially the smell.
And no, there was not an extra charge for the service. I just called and requested it of central booking.
Hope this helps.