I never grease bb tapers. It only makes your crank wear quicker. Without grease, sometimes the crank will need a little torque check after the first ride, but it's a small price to pay.
I haven't had an unusual amount of bb loosening with greased Italian threads, though it seems some frames or bb's or the combination thereof don't hold as well as others. My first choice in this case is to reinstall the bb using a small amount of grease and teflon thread tape. If I still have problems I'll clean everything up and use a light loctite on an otherwise dry bb and frame. Not using anything between the bb and frame is a recipie for a giant pain when removing the bb after long use and abuse.