I heard a lecture by a Buddhist Nun and according to her, for Kharma's sake, thoughts do count. My memory is hazy but I recall that Right Speech, Right Action and Right Thought are all basic tenets and goals of a Buddhist follower.
If you are dominated by these thoughts, they probably influence the way you behave outwardly if only by making you dull at parties.
I recently had my first tooth filling. The feeling of half my face being frozen was interesting to say the least. I'm reading a collection of Horror stories from the 19th and early 20th century so my thoughts while driving home leaned toward the macabre. Playing with my dead bottom lip I contemplated the painless ease with which I could cut the thing off for fun and experimentation.
It's an insane thought (and good fodder for a story) and somehow at the time it was truly tempting. But the thought passed as the anesthetic's grip faded. I don't believe that passing grotesque chain of thoughts makes me insane but I guess as in all aspects of character, it's a matter of degree, ebb and flow.
Anywho, welcome to the board.