I just finished building a 3770K + Sabertooth Z77 build. I bought the CPU + motherboard from Microcenter. I got everything home, built it all inside the case, then I removed the CPU protective cap very carefully (I've built LGA systems before!). Underneath was a mess of bent pins in the three out of four extreme corners. I know it wasn't me because I was extremely careful, and the amount of bent up pins was pretty extreme. A bit frustrating, as I had to take the motherboard back out of the case (and unplug power, SATA, RAM, etc.) and drive back across town and do an exchange at Microcenter. I inspected the new board while still in the store to make sure the new socket was in good shape (it was). Microcenter handled the exchange without any issue, which is why I like to buy stuff from them when I can.
So, a couple of hours later, things are just dandy. 3770K, Sabertooth Z77, GTX 670, 16 GB RAM, Corsair H100, Seasonic X750 Gold, Samsung 830, all living in a Corsair 650D. It's... pretty damn fast. Overclocked to 4.5 GHz without any problems, seems to be running a bit cooler than I'd expected.
I've never bothered bench building a machine, I've always just build it in the case and it's always worked the first time (until this). Maybe next time I'll bench build it first.
Anyone else ever seen a trashed LGA socket from the factory before? I still have faith in Asus, stuff like this happens.