There's always a chance you'll receive a DOA or defective motherboard. It is fairly uncommon, but certainly not unheard of. With the X99 platform virtually all motherboard are targeted at the higher end of the market and have very good features and high quality.
The higher number of features, some of which are very new to the market combined with the fact that the X99 market is relatively small means that you do run a risk of receiving a dead or defective motherboard, but for the most part you should be fine with any motherboard.
If you are unlucky enough to receive a faulty board though then it's standard procedure: request an RMA and get a replacement. ASUS is known to be a bit picky and specific when it comes to RMAs, so maybe avoid them. Their boards are very solid though, and are considered to be higher quality ones by some. This is not always entirely based off pure facts however.
These are my personal top picks: https://pcpartpicker.com/parts/compare/asus-motherboard-sabertoothx99,asus-motherboard-x99a,gigabyte-motherboard-gax99socchampion,msi-motherboard-x99agaming7/