Guppy, I would never dump actual food scraps on top of my litter for the birds to 'scratch into the bedding" for a few simple reasons. Some food scraps won't get eaten and will sit there and rot, attract gnats and flies and won't do a bit of good..they will sit and mold/decay. The second is for the reason you mentioned...I don't put their food where they poop. They are bound to consume some manner of fecal material in their lifespan but actually placing large pieces of food on the manure isn't something I would do. This is one reason I don't recommend folks scattering their feed in the run for them to "have fun scratching and pecking"...that's okay on occasion and if they are using a deep litter that digests manure, but on a barren run littered with high levels of fecal matter, it's just not sanitary to be eating past poop every day and compounding intestinal pathogen and parasite loads.
In the winter I have scattered BOSS in areas where feces is most likely to be deposited on days when they are confined to the coop for deep snows but these are slick and tiny seeds that do not adhere to feces like, say, a broccoli spear would. The BOSS is small enough to filter down past any fecal matter and must be searched for, thus would indeed cause the feces to be moved and worked into the bedding without it actually having much contact with the seeds.
But...that's a rarity and only when I have BOSS on hand and the birds have been confined for several days. Usually I don't have much concentrated feces in the coop as my birds free range all the time....
Thanks, Beekissed, this confirms/clarifies things for me. And for the tip on BOSS (black olil sunflower seeds). Inside my coop, I have dried grass clippings/straw on top of some type of soil covered with a thick layer of what I think is lime, which the prior owners put down many years ago. One time, the coop flooded out so to help the ground dry, I pulled off all the straw and daily, spayed up 4-6 inches of dirt to air it out and help it dry faster. There are NO worms or bugs in the soil so whatever is covering the floor does not support composting organisms. I'm thinking about converting to deep litter and to do so, I'd have to layer some compostable materials on top of the existing lime-type dirt and assume that the lime dirt will act more as a composting barrier vs. what normal dirt/soil would be.
Just thinking this through.
Guppy