In this sense yes: Every language is a convention and convention implies rules. A non-standard variety of English has its rules and so anything that does not conform to the rules is "incorrect".
In this sense no: If you are taking Standard English as the yardstick to measure other varieties then they will of necessity be incorrect and so the notion of even considering whether correctness applies to them is contradictory.
In this sense it depends: There are no absolute canons of correctness in any language variety. The best you can say is whether or not a purported instance of the variety is expected or not according to what you know of the variety.
The real point of course is that when speaking a non-standard variety one is not troubled with notions of correctness.