I use the small upholstery attachment on the vaccuum cleaner. The nozzle to get under the rails and the 5 inch wide one for the bedcloth. Just make sure you vaccuum from the head of the table to the foot. Then brush it afterwards to get the "grain" of the cloth all going the same direction.
I also use the Woolite upholstery cleaner when I do have to clean a bad spot on a bed cloth. Lot cheaper than the Chalk-off stuff and seems to work the same. Plus I can just go to the grocery store for it.