Mine get all leftovers, anything we have eaten. I figure if the mold in blue cheese is ok for me to eat it won't hurt the chickens. HOWEVER- I never give them any kind of moldy food (cheese, bread, coleslaw, fruit, etc) that's not supposed to be moldy. As for potatoes, mine eat cooked ones all the time, skins and all. The skins that might hurt them are the ones that are green (something called "solanum" sp?) which I would peel off if feeding to my family so I just avoid feeding them any raw potato products.