UnklRod,
If your are using a vacuum bleeder, pull the bleeder valves and wrap them with 2-3 turns of Teflon plumbers tape. That way, you won't suck air when you are trying suck brake fluid. Leave the tape in place when you are done, it improves the seal.
Teflon tape on the threads wil help duting bleeding by keeping the it from sucking air around the threads of the bleeder, but will serve no purpose afterwards as far as sealing. The bleeders seal against a machined seat in the wheel cylinder/caliper. the threads do not seal gainst the fluid like a pipe fitting. The tape will prevent corrosion in the threads, though.
