Bathroom Window Coverings

Our bathroom window faces directly to our neighbor's house about 50 feet :-(

I suggest you consult your craft store, Home Depot or Lowe's for a window covering self-adhesive. It is an adhesive sheet that will make your glass on the window appears as if it was frosted. This would give you some privacy but not block light in your bathroom. Finally you can choose mini blinds, but they do not dust!

Nothing will rot or start to smell. I had the same cotton curtains suspended for 5 years.

50 feet is too far to worry.