I get few link requests, but the vast majority are right on target, written by the business owner, or at the direction of the business owner. They are usually sites that I would have linked to anyhow, if I had found them before they found me.
I don't bother asking for a link back. If they do link back, fine, if not, that's also fine.
I have done a couple, maybe 3, "link exchanges". They're more bother than they are worth.