“Code Smell” is a signal. A hint from the code itself, that there might be a deeper issue with it. Not an immediate problem though, but rather a potential long-term affect on the code quality and maintainability.
Here’s a thought: code comments, often seen as helpful, are actually a code smell. Why? Because they are either redundant – adding to the mental load, or an indication of the fact that the code is overly complicated — too much context, too many tasks being done, mismatched abstraction levels, etc.
Comments aren’t inherently bad, they have their place. But if there’s a comment, there’s often an opportunity to improve the code.