There are over 60 diseases in pigeon poo so you need to have the proper ppe and be very careful.
Never take chances with your health so always charge accordingly.
Since you are dealing with a serious health hazard, charge more than normal washing.
I bid on an abandoned warehouse that had up to 1" mostly on the floor and in some places up to 4" of bird poo. I gave them the estimate and explained how hazardous the job was.
They got some day laborers from what I heard to clean up the mess, I feel sorry for those guys as I am sure that they did not know what they were getting into and probably did not have the proper ppe to stay safe.