There are those who remain convinced that Louis II of Bavaria (Ludwig II von Bayern) wasn't mad.
I had a similar conversation with someone a short while ago. "He wasn't mad, just misguided". he said.

It is simply impossible to argue with people who are obsessed with Louis II. If you come up with texts and such, they still will not believe you.
The most they would admit to is: "he might have been a bit eccentric".

This kind of topics might be a nice addition to this thread (shady side of history).
Some people are willing to believe every bad thing that is said about royals, while others remain convinced that people with noble blood are perfect and never make a fault or commit a crime.

"Royal mysteries"
suggestions to possible subjects:

1) "Louis II was declared mad as result of a Prussian conspiracy"
2) "What happended to Philips von Koningsmarck?"
3) "Who was Casper Hauser. A long lost prince, or a fraud"
4) "Was Peter III murdered, or was it just an accident"
5) "Marie Antoinette and the infamous necklace-affair"
6) "The mysterious death of archduke Rudolf of Habsburg"
7) "Did Nostradamus really foretold the death of the French king?"
8) "The princess who believed she had swallowed a true-size glass piano"