I always just eat meat based on the smell. If it does not smell bad, it is fine for me.
I use smell for dairy, but for meat, I use the color test. I've learned that when lunch meat starts to take on blue and green hues, like the way oil on water looks, it's only got a day or two left.
My role in the family has always been to eat the things that are "iffy." We don't like to waste food.