Hi Chris
you can when customers with pale coloured curtains complain about having them back from the dry cleaners complete with a grey or yellow discolouring because they have been cleaned with other items in the same batch or runs many loads with the same dry cleaning solvent to save money! at least the fluid we use is only for that item,some pelmets are actually fixed by staples and the home owners don't even want to attempt removal for fear of not being able to re-fit them properly! some curtains we do would not even survive in plant cleaning either due to the sunlight,humidity,heat and pollution oxidising them,and some pelmets are reinforced by cardboard which would never survive;D
all the best
John