Well, I probably flew the CENTO route by day and by night as often as anyone else. It was always stressed that our Russian friends "just over the border" had NDBs on the same frequency but much more powerful for the unwary to follow.
Did not a US military C-130 fall foul of this?
What I do remember was being told that a lot of the power supplies to the NDBs were compromised by the locals looking for a free power supply in the winter!
Just imagine that you live halfway up a Turkish/Iranian mountain covered in several feet of snow. By lucky chance there is an NDB nearby which contributes absolutely nothing to the local economy as far as anyone can see so why not tap off the electrical supply for the winter for absolutely no one is going to battle up to the beacon in deep snow to see what is going on until springtime?