Sauron's Great Miscalculation

[Mithadan]

By "poor intelligence" I assume that you mean lack of strategic or military intelligence, i.e. where is the ring, as opposed to pure stupidity. Or maybe I am wrong.

The lack of "intelligence" relates to the efforts of Gandalf in concealing the path of the Ring, and, candidly, Sauron's failure to perceive that his opponents might seek to destroy the Ring rather than use it against him. So, perhaps, Sauron's "poor intelligence" was really a lack of understanding. The Ring was not being brought to Imladris to be wielded. It was not being brought to Lothlorien to be wielded. It was not being brought to Gondor or even Rohan to be wielded. it was not to be wielded at all, but rather destroyed.