They're not falling-down stupid; they radiate the subtler variety of idiocy that can be mistaken for charm, decency or even brilliance.
The reasons for the new American austerity are subtler, but not shocking.
More recently it has been joined by subtler techniques that go beyond what you say, and analyse how you say it.
On the other side of the planet, the signs of water that led to Meridiani Planum being chosen as a landing site were much subtler, making it more of a gamble.
What if, for some one of the subtler reasons that would tell with both of them, they should tire of each other, misunderstand or irritate each other?