Stormy,
How many turns on a toilet (I guess you'd have to lift it up and tip it ove r, better wear boots) does it take to
*loosen a joint* enough to leak? If you've ever done any amount of plumbin g, you know you don't have to unscrew a fitting all the way to have it leak . You just have to loosen (or tighten) a tiny tiny bit past where it shoul d beI don't put Teflon tape on a toilet, come to think of it.
There are lots of plumbing joints that are subject to high vibration, becau se there's a recirculating pump or other motor shaking them constantly. Do you avoid Teflon tape for those?
Shotgun choke tubes are commonly installed with teflon tape, because otherw ise they tend to stick and can't be changed out. These are high temperatur e AND high impact joints where shaking loose could be a VERY bad idea. Out board motors have a number of joints commonly installed with tape. None of these are tapered threads. So it does work, you just never heard of it be fore.
I don't like tightening any fastener dry, whether tapered or straight. Thi s is because I believe you can't get the torque accurately enough dry, you have too much friction to be sure of the right amount of torque. I've alwa ys lubed joints of any kind, but recently learned tape can be a lot less me ssy while still lubricating and allowing easy removal.
Of course torque itself is meaningless; the purpose is to make sure your bo lt is loaded to the correct amount of tension and never in shear. But we c an only measure torque.