Originally Posted by scoho

This is one of those cases where both sides of the argument make perfect sense to me. The other side here being that lubrication can lead to bolt over-tightening and consequent deformation of the spindle and crank (because the lubrication encourages the crank arm to slide farther onto the taper than it should at a given torque).

Personally, I split the difference: Apply a super thin film of grease to the spindle, just enough (I hope) to provide a barrier but not so much (I hope) as to promote slipperiness. I have no idea if this works.