Jballou: But I can use your own logic against your argument. The adverb (not adjective) doesn’t change the actual verb. The verb can either be LOOK or IS. I think that is where people get confused, whether to apply the adverb (deceptively) to its appearance or its actual state of being.
It can be doubly-deceptive—in appearance and then in its actual state of being.
If you substitute “surprisingly”, it might be less…confusing?
If an object LOOKS small, but IS large.
The object LOOKS surprisingly small, but IS surprisingly large.