It's totally based on luck.
Some stores actually hold their standards pretty high on the CE's they accept and take in, and some don't give a crap, so it just depends which store it comes from.
I've gotten some nice complete condition CE's before, and then a few came in the condition Vinny has mentioned, which was pretty crappy, but depending on the price, may be worth the risk.
You can always return it if it doesn't work out since their CS is pretty good.