My understanding:
As discussed in numerous articles around the web and other media (some wirh extensive legal analysis), the FAA maintains that they have sole legal jurisdiction over airspace, and they regulate it under parts 331, 333 and 107.*
However, many communities, state and local governments have enacted, or are considering, regulations governing drone use - often in conflict with FAA jurisdiction. While most local governments clearly can limit operation of sUASs from public areas over which they have jurisdiction, the FAA maintains that only they can regulate aircraft operation in the airspace. In other words, the locals can regulate what you do with your drone on the ground, but may conflict with the FAA if they attempt to regulate aircraft operation in the airspace.
This has set up situations all over the country in which local governments are attempting to usurp FAA authority. Consequently, a sUAS operator might be cited for violation of a local ordinance while conducting a flight that is in compliance with FAA regs. Assuming the flight did not violate any other ordinances (e.g., taking off from a public park where drones are prohibited, or obviously invading someone's privacy), it would make an interesting court challenge of the local ordinance.
*There is some ambiguity regarding how far above the surface "airspace" under FAA begins. Some authors claim that an occupant of the land has rights up to a height at he can reasonably be expected to use it. Others cite old case law that mentions a specfic altitude. Some local governments appear to be ready to make a legal argument that they can regulate activity in the airspace up to hundreds of feet - effectively eliminating the only area sUAS opertations are allowed by the FAA.
So long story short, it's probably OK with FAA to fly over abandoned industrial facilities (assuming you've complied with all the regs)... but you still might get busted for violation of a local ordinance (that may not, itself, be legal).
As stated above, this is my understanding...and the situation is evolving.
