@Go Habs Go,
I am afraid I have to disagree with you. The point behind saying "I speak well" but "I smell good" is not simply an arbitrary one where sensory verbs go with adjectives, and all other verbs go with adverbs. It has to do with what word is modifying what.
Adverbs modify verbs or other adverbs. So they tell you how the verb is done. In the example "I speak well", the well refers to the act of speaking, which is done well.
If you are talking about sensory things, e.g. "I smell good", then "good" is obviously not modifying the act of smelling--you do not mean "I am a good smeller". You want instead a word to describe you the subject, how you smell. So you use an adjective, which in this case modifies the thing itself, not the action being done.
This is why it is correct to say "I am good", because YOU are the thing that is good, not your act of being. Translated into Tarzan, me=good, not am=good.
I am sure that there is probably a long history behind saying "I am well" to refer to one's health instead of state of mind or whatever. But my suspicion is also that a lot of people say "I am well" because they think it is grammatically wrong to say "I am good", when it isn't.
For some reason, English grammar is really hard to learn correctly while you acquire it, and this has led to a lot of people being really confused about correct grammar, and trying to change their speech for the better (admirable), but who are often poorly informed (not so good).
Things like "Her and I went to the store", "she gave a present to you and I", etc.