Not to go off topic, but...
Does it make sense to purchase a ST warranty on a refurbished camera lens? The lens is the Nikon 18-200mm f/3.5-5.6G ED IF AF-S DX VR II. It comes with a 90 day warranty.
I'm new to the DSLR world and not sure about what issues may arise with lenses.
There is virtually no reason to purchase ANY squaretrade warranty. The odds are against you coming out ahead. As a rule, you should not buy a warranty or insurance coverage unless you are buying something that you NEED to have and you will not have the money to replace it if something should happen to it. Do you need to have this lens as a part of your job or some other reason? Could you replace it with your own money if you had to? If you answered no to the first question and/ or yes to the second, there is no reason to purchase the coverage.