The smells in this chapter are the easiest to identify. They're not necessarily the easiest to fix.
There are other metrics that have been applied to software. Many of them are simply refinements of code length. Pay attention when things feel like they're getting too big.
There is not a one-to-one relationship between refactorings and smells; we'll run into the same refactorings again. For example, Extract Method is a tool that can fix many problems.
Finally, remember that a smell is an indication of a potential problem, not a guarantee of an actual problem. You will occasionally find false positives—things that smell to you, but are actually better than the alternatives. But most code has plenty of real smells that can keep you busy.