I'm suspicious that it's from the loo roll but everybody else has a nice dust free bathroom. Maybe they dust every day.
I mean every nook and cranny, the plants, the bottles, the bath toys, the window sill, the tiles, all of it's covered in a thick layer of dust. I could dust and Hoover the entire room daily and it just comes back. I have pets but they don't come upstairs (the cat does but he's the least dusty) and otherwise I have no idea. Do I just need to exfoliate more? 
Any suggestions that don't involved crawling around with a damp cloth daily are welcomed.