dwarves should be able to piss the bed if frightened by ghost/injured groin while sleeping. you should add a laundry job zone for running water/rivers, or a laundry job at a placeable bucket that uses lye to clean soiled sheets/clothes as an automatic job. in the next update, add pooping.

Suggestion:

Another version of this mod with bed sheets included, and its own special reaction.

So there would be the normal reaction, Assemble Bed, which would function as it does presently, and then there would be a second, special reaction

Assemble Luxury Bed:
A bed which has 2 components, a bed frame and bed sheet. Produces a bed but with a special in-built decoration, the bedsheet! Thus improving the quality of the bed! And you can further decorate it too.

The "Luxury Bed" would just be a bed with a special in-built decoration, being the bedsheet, but is otherwise a normal bed.

How about adding some bed sheets?

[REAGENT:bedsheet:5000:CLOTH:NONE:NONE:NONE]
[WOVEN_ITEM]

Nothing else, just the bed frames.

So, you can make bedframes from many different raw materials. For assembly at the Craftdwarf's workshop, what do you need besides the frame?