We've hashed and rehashed what things may make you think a cook is not very good, but what makes you have faith in their cooking skills or at least the tastiness of the food they'll churn out?
For me, it would probably be:
Lots of fresh produce and a freezer full of "from scratch" items, like beef stock, pasta sauces, enchilada sauce, etc.
This is obviously problematic, but not too many "single tasker" gadgets that could otherwise have their job done by something else.
Well-used items, like stained silpats and heavily scoured stainless pans.
Fresh lemons and garlic in the pantry, not for decoration.