Why would the facility need to be camouflaged when it's already at one of the most top secret military facilities in the world? You can see the dozens of huge hangers at area 51 that we already know contained secret projects, Skunkworks etc..
The remoteness, massive perimeter, no fly zone around area 51 already gives it sufficient protection. Military command centres are a different type of facility built deep into mountains since they will be initial targets for air strikes. Defensive military installations (like the camouflaged barns and such in Switzerland) also could be camouflage for strategic defensive purposes near perimeter of the border. But I don't see the reason simply for a secure research facility. I'm sure area 51 has bunkers in the mountains, some probably containing projects requiring material shielding, but the entrances and exits don't need to be extremely camouflaged to look like undisturbed desert. Simply being in one of those hangers at A51 makes it impossible to know about without leaks.
Secondly, if indeed there was a massive facility on the scale Bob asserts, surely we would see significant tailing piles in the vicinity. We are talking thousands of dump truck loads which would've been removed