How much would you have to be paid to walk over hot coals?  What if how your feet responded to being horribly burned was going to determine whether or not you were executed?  

How much would you have to be paid to have an operation that made it so you could never lie?  Would you be willing to be committed to an insane asylum if it was a really nice one?

Would you be willing to have a man over for dinner if you knew the following things about him: crazy from extended mercury exposure, cut off his own testicles with scissors, and shot John Wilkes Booth?  What if Lincoln was there too?