For sentences like "I smell bad" I'm confused on the role.of the word "bad" and whether it requires a suffix. On the one hand it seems that the properly formed sentence should be "I smell badly" but on the other hand it seems to mean something entirely else.
Are these two different, well-formed sentences (bad vs badly)? Is the first (bad) just a convention of conversation and only the latter form (badly) valid but just ambiguous (do I mean that I smell of badness or that I have no talent for scent?)?