Depends. I bought .hack3 earlier this year from CC and PSP-Sp2 from KB, both for $10. Traded them to Rhino for a brand new game last week. Is this flipping? Technically, yes. But I don't consider that wrong.
I don't even neccessarily look down upon getting a deal for a game and trading it right away to somewhere else for more credit.
I do this all the time, and honestly don't even remotely see how someone could see anything wrong with this. Where is it wrong? That I traded a game I didn't actually play? Or that I traded a game that I didn't lose money on?
I reguarly buy games specifically to trade into my Rhino. And you know what I've noticed?
A) The employees do the same thing. I've overheard discussions where they were talking about upcoming CC sales as ways to get qualifying games cheap.
B) Every other customer that's traded something in while I was in the store has NOT taken advantage of their deals. Using your head and taking advantage of promotions is not a wide-spread activity. Usually, I see these people giving away their games - trading a qualifying game by itself, or trading in a bunch of non-qualifying games for little or nothing.
If these trade-in deals were losing the store money, they would stop them. The fact is, they get 2 games in brand-new condition that they sell for $25 (at least)/ea.