Saruman's Pits

[Inziladun]

Originally Posted by Legate of Amon Lanc

So I think it is the combination of all of the above (except the illusion). Strategic placement of the pits that they are not right under everybody's nose when they arrive. Limited visibility after dark. Gandalf's mind preoccuppied by "what are we going to do about the Ring?", "the Nine are abroad!!! We're doomed!!!", "I hope Frodo is still alive", "oh no what if that fool of an innkeep didn't send my letter? I'm gonna fry him" and "oh no, I have to make this arrogant colleague listen to me and endure his wannabe-intellectual condescending comments before we get to the heart of the matter". Saruman's Voice as a bonus. I don't think we need more than this to explain that no pits with Orcs were visible when Gandalf arrived.

Good points. I think my main opposition to the camouflage theory leading to the "strategic placement" of the pits is the question of exactly who Saruman would have had in mind when planning how to hide them.
Who went to Isengard? Really no one, apart from Wormtongue. I get the impression that Gandalf and Radagast had not been there for quite a while before the event in question, and they only went because they were summoned. I don't think Saruman would have been worried about the Eagles seeing what he was up to, because before imprisoning Gandalf he was a known ally, and no one would have been watching him.
So, how much trouble would Saruman have been inclined to take to conceal his pits and forges? In his pride, too, he may have thought he was naturally smarter than the rest of the Wise, and have not thought them a source of worry.