This is the only category I don't think should be in the bannable (?) list.
Many "tin foil hat" allegations have been documented to be true later. Discouraging discussion on what some people think is too far out there, would inhibit knowledge being shared. Let the members decide what is, or is not, a "tin foil hat" posting. FReepers are usually quick enough to demand "Cite your source".
Once upon a time, government mind control and Cointelpro were "tin foil hat" territory; then Congressional hearings exposed them to be real.
Saying Lee Harvey Oswald was not the (lone) killer of JFK would earn you a hat; where now even the History Channel runs a program "The Men Who Killed Kennedy".
And black helicopters, the be all and end all of "conspiracy nuts", were confirmed by named government sources in The New American magazine.
The Oklahoma City bombing, I think, will be the next to fall. And I'd like to think OKCSubmariner's (a top notch "tin foil hatter") efforts and research contributed to the outcome.
After my ramblings, tin foil hat postings should be the first place where "..., you decide" is the rule.
It was in late 2000.