What not is hard to explain, no one really knows what it is because its not.
Okay, it goes like this. Tinfoil hat loosely refers to something that is deemed too wacky to be believable. It seems to me that there are basically three camps of believers as per "tinfoil-ia."
1: Rabid, foaming at the mouth, all tinfoil-all the time.
2: Middle of the road, basically open minded folks who know that there are things that can't always be adequately explained to everyones satisfaction.
3: Rabid, foaming at the mouth, "electricity is tinfoil!" type folks.
Here's an assignment for you: Start a thread about, oh, let's say, contrails, and you'll get all three camps, all stating their beliefs. That is, if the thread isn't pulled first.
Try it, sit back, and observe.
According to those who know from experience with gummint conspiracies, tin foil on your head is the only protection against the radio microwaves transmitted by the FBI, CIA, NSA (substitute your favourite acronym here) to control your brain!