Or instead of spending hard earned cash on protectors you could always dip your fingers in a harsh acidic solution and chemical burn your finger prints off.
I do not advise this It was just a funny thought that ran threw my head when I read the threat's title.
The other thing to think about is installing an app like "mylock".
I used to turn off my screen, wipe off all the nasty, then when I'd turn my screen back on I'd have to slide the lock and there's a smudge right off the bat.
With mylock you turn on your screen and don't have to swipe the lock.
For smudges, I find that the front of an Under Armour tee or polo shirt works pretty good.