Even when they appear to hold totally divergent views?
Damian Thompson's excellent Counterknowledge offers us a suggestion as to why.
"An author who believes that Stonehenge was built by Aztecs will cheerfully recommend the work of someone who thinks it was built by the Priory of Sion, because they both recognise their real enemy as orthodox scholarship". p.79
In other words it is not the theory that matters, just the fact that it is an alternative theory. Sad isn't it?