My closest store is a Walmart Superstore and I won't use it for groceries if I can avoid it. Pretty much everything in it is heavily processed (grape flavored apples anyone?).
Very little is from local farmers and the only organic fruit/vegetable they stock is cauliflower if you are lucky. The meat is all factory farmed.
You can make bad food choices wherever you go of course, but it is very hard to make good choices in Walmart.