This is an interesting question. I don't know if it makes a difference, but if I'm reusing old speaker wire, I clip off about an inch on the ends as a matter of course. If there's a lot of oxidation, I usually just toss the wire. It's hard to say whether this would really make a difference, but it makes me feel better. On the other hand, if there's no oxidation, I wouldn't really worry about it.

I am the Doctor, and THIS... is my SPOON!