Yes it's a digital but only a harbor freight unit, but it does read 0 when the tips are touched together in the ohms setting, and the voltage does read 120V when in the A/C volts setting and hooked into the receptacle, and 0 when not touching anything, and no I don't trust that the readings are super accurate but probably not horibly off due to the fact that when I did touch the red lead to a positive and the black in the dirt I still got 100V as compared to the 120V that I got when connecting the black to the neutral side.
So far when I was reading the prongs on my 50a power cord, I got a .5ohm reading from the ground/round prong to the bare metal on the RV (a bolt on a compartment door hinge) that I was testing from, so according to a few posters it should be good if less than 1ohm. When connecting from the groud/round prong and trying to read through to the other prongs on the plug I was reading infinite. I do have a transfer switch/surge protector built into the RV and it may have been shut off as it only seems to click once the breaker is turned on.
On a positive note, the voltage reading (although crude as I know) does not change weather the circuit breaker is turned on or not, so I seariously doubt that the problem is in the RV as in my thinking, if I had a short to ground, the voltage leading from my bare metal to the dirt should rise at least something.
I could probably get a better ground if I soaked the dirt near where I'm testing but didn't want to give myself any more of a chance at getting shocked more than through my tennis shoes.