Inspired by this question, which was closed because (and I agree) was not asked correctly and is not answerable.
What are the criteria to convert code smell to a bug?
Code smell is a hint that something has gone wrong somewhere in your code (not a certainty, not a bug).
So what would be good process/criteria to decide which smell is a bug, and which is not a bug yet?
Linked page gives many examples of code smells (excellent introductory reading), and c2.com wiki - the first, original wiki (since 1995, and still around) -- is great learning resource overall about design patterns, extreme programming, and all stuff related to programming.