I think that a sure sign of quackery in Internet comments is someone who adds a quotation at the end of each of their comments. You know the ones, they spout some bullshit and then add "Liberty is the residue of Freedom: Thomas Paine" at the end.
So I just saw a comment that included a quote at the end. A quote that was unrelated, like most of them, to the comment itself. Here's the final quote:
"Parachutes are allowed in check-in or carry-on luggage, but may not be worn in flight.