I don't really see why you have to bring linking verbs into it (but I'm not the best teacher to ask about linking verbs). I think you're right, but wait for another teacher to confirm this. You are certainly right that 'He smells badly' is wrong - whereas 'He spells badly' would be right.
This recalls the music hall joke:
My dog's got no nose./How does he smell?/Terrible. [bou-boum, tish]
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