I can't remember which old book I read it in, but a seasoned veteran of chicken husbandry commented that all you needed to do was look at a chicken's feet to determine how good of a forager it was. If the nails were long and pointed, then that birds prefers the feeder. If the nails are short and rounded then you have a good forager. It's definitely proven true of my birds.
That's true in most cases, though my WRs have better feather and nail quality than the BA and most other hatchery stock I have, so their nails tend to grow longer and stronger than hers but they all forage equally well. That's sort of like saying women with longer, strong fingernails must not do any housework, but my nails grow like crazy and withstand heavy work, whereas Mom's are paper thin and break over nothing. I have thick, longer hair and her hair is woefully thin and won't grow well.
But, for the most part, a dull nail on a chicken would indicate more foraging done and more foraging opportunities available.