Well-aged beef is hung for as much as 30 days until it goes green. The green is scraped off and you have a very expensive, tasty piece of meat. Beef in my fridge goes off after a week or two and if I eat it I will get sick. What is the difference? I'm sure the first responses will talk about specific types of mold. Are the ones in aging not harmful? If I eat that green piece of meat, I'll still get sick, right? And no amount of scraping will get enough off that I won't still ingest large quantities. So what gives?