The fact you had to clarify "at dancing" is why they're different.
Think about it as a decomposition where "dancer" means "dancing person."
In the simple case, both "blonde" and "dancing" separately modify "person." If you diagram that it’s a Y: either modifier could be removed without changing the meaning of the other, and their order isn’t important.
In the complex case, "bad" modifies "dancing," which together modify "person." That’s an ordered chain, which is more complex to build and comprehend. Your clarification illustrates the chaining and why it’d be a fundamentally different meaning if that wasn’t understood.
I’m not even touching whatever you were going for with the blonde/brunette thing. It's plain they used the example because there's no possible way hair color could be a modifier for "dancing," and they wanted something unambiguous.