"I always wanted to be a good guy."
While speaking, I could make this sentence mean two different things by simply placing different emphasis on the word "good." If I wanted to say that I always wanted to be good, I would place emphasis on the word good. If I was trying to make it sound like I was trying to be a good guy (as opposed to a bad guy), I would say the words "good guy" together and more quickly.
Does that mean that in the first context "good" is an adjective and in the second, a "good guy" is a noun by itself, or is "good" still an adjective in both cases?