I believe the correct answer is related to specificity, ie what is most important to what you’re communicating.
To borrow some parentheses, (the big (bad wolf)) highlights the character of the wolf as being more important than it’s shape. However (the smelly (bad meat)) emphasises the bad-ness, or rotten-ness, of the meat and further describes it as smelly.
Similarly the focus of (the bad (old days)) the past, and bad is acting as an adjective for (old days).
To borrow some parentheses, (the big (bad wolf)) highlights the character of the wolf as being more important than it’s shape. However (the smelly (bad meat)) emphasises the bad-ness, or rotten-ness, of the meat and further describes it as smelly.
Similarly the focus of (the bad (old days)) the past, and bad is acting as an adjective for (old days).