def eat them, there isn't anything to worry about. If they look sick, toss them. However in the prob 150 squirrels i've eaten so far, i have not had one that was anywhere close to being sick or not edible. Always have been clean w/ not even a tick or mite on them. You can skin it, and you don't even have to gut it, just cut off the legs, the only other meat on them, is a small amount (and only on the big ones IMO) that goes along the spine on the outside of them. the 'backstraps' or loins. But in general all the meat is on the legs especially the backs. the meat on their sides where the ribs are is very tough and different than the leg meat and i do not care for it.
Squirrels are what got me into hunting, and i still enjoy hunting them. If you cook them fast like frying or something they will be like eating rubber. bread them, grease a tray and put them in the oven, i use convection for 1 hour at 325F and it works perfect. Like baked chicken legs, limb chicken that is
Being a squirrel hunter, i'd say kill the ones in the attic, and do a little home modification to prevent others from entering. I'm not one for trying to eradicate all of them in your yard. I guess i just have respect for the squirrel
B/c in no time more will show up and it's never ending and not 'fair' to the animals, especially if they are not being used. And if you do kill them in the backyard, ones that aren't actually in the attic nesting....watch your self b/c in many states (here in NY this is true) they are a GAME animal (does that tell you if they are good to eat!?) and have seasons and hunting rules and regs governing them.
keep the shots to the head at the eyes or a bit behind, or right at the front shoulder. gut shots, even with high velocity HP .22's do not anchor them and many will get away wounded. I find them incredibly tough, and have hit them with good shots and had them get away or take a much longer time than you'd think to expire.
