TOPIC: GFCI in non grounded house

Like anything else, "if it is functioning as intended" it will open the circuit thus protecting the woman in the bathtub." How much current she gets, a little or a lot, is the variable. AS an inspector, you are there to test or inspect the devices as functioning or deficent.

You, as an inspector, and in my opinion, would not want to warrant or gaurantee that she will be protected from harm inclusiveley. Any more than if the house DID have a three wire system AND three pronged receptacles AND was grounded.
So either way, the lady, as far as we all know will be protected to some degree IF the device functions as it is intended to function. If she takes a current and the device does not open as it should, what do you think will happen?
But your job is to inspect. Maybe I misunderstood you as my original comments involved the need for special attention will inspecting GFCI functionality in two and three wire systems. 

Hi Michael. The answer to your reply# 2 is No. A handheld testor works off the circuit ground wire ONLY. That's why wire with an ungrounded circuit (two wire), you test the receptacle by pushing its test button, then check for current with a light or voltage tester to make sure the circuit is open. In other words, on two wire circuits, it is a good practice not to use handheld testers, in my opinion. I'm sure others might disagree, but that's what I do. Challenging ourselves with questions like these keeps us sharp! Thanks.

Two wire systems MUST be tested using the test button on the receptacle or circuit breaker only.  If it trips using the built in test button, report it as functional and move on.  If your wife throws the hair dryer or radio into your tub, the GFCI protection will be the same regardless if it is a 2 wire or 3 wire system.  Even if you use a 3 light tester or bigger SureTest, always test using the built in button as well.  I always test both top and bottom of the receptacle.  You would be surprised how many will trip with one and not the other.

Thanks guys. I have an older house that does not have a GFCI in the bathroom. Now if I can just find the darn hair dryer while my wife is taking her bath..... ;D ;D

YES..Micheal, it still will Work!
The GFCI  measures current incoming on the hot wire and compares it to the returning current on the neutral wire.

Thanks Dan, and thanks to all who replied. Dan's answer was the best, he was precise and cogent. "Brevity is the soul of wit".