Lotery teams are more likely to make trade in confs out of confs or any where they can, but Perennial playoff teams usally don't.
As far as OKC, flipping Harden for Kmart seems like a good trade for both teams but down the line, what if, Dwight Howard dicides to go to Houston? Dwight Howard and Kmart doesn't scare anyone, but Dwight Howard and James Harden is something you have to deal with.