Newegg has gone down hill dramatically since they incorporated dozens of unvetted online retailers. Even if something says it will be sold and shipped by newegg, i have already had more than one order where it was actually shipped from some random retailer.
That said an RMA within the 30 day window should be accepted regardless of the condition of the motherboard or reason cited in the RMA. I could see damage coming up in a warranty claim, but not an RMA. They do charge a fee for returns, but i believe it is waived for exchanges.
Newegg isn't a shady company, and it is no skin off their back to send a board back to the manufacturer. I'm always very wary of peoples stories when it comes to RMAs and retailers. Just like motherboard...