The goats will see it as food so if it gets dirty they may still try and pick through it vs. the straw they usually won't eat any. Eating the dirty hay can lead to quick parasite overloads. You could try it out and see how it goes. If you use the leftover hay the goats won't eat...that would probably work better.
My goats won't even think about eating hay that they have peed or pooped in - used to be quite a problem when they could jump into their hay feeder , pee in it and then refuse to eat it. I use the hay that I rake up from my hay storage. Here hay has gotten super expensive so I only use waste hay for bedding.
DayDream Farm Mini LaManchas
hay is really expensive. My goats will pull hay that they don't like out of the feeder and drop it on the floor so I just use that and try and muck our once a week or so. Basically the same as Luvmygoats and freedomstar
Merry, Pippin,(saanen harness wethers)