Surely if the VOR is East of your position you will be on the 270 radial and would need a 090/270 OBS selection to get "to" or "from", respectively. Why would you ever get a reading of 000?
thats precisely why i posted the question
It's true to say slant accuracy increases with range but then DME is line of sight so eventually accuracy will decrease with an increase in range, as you pass beyond line of sight of the transmitter.
i was also thinking on these terms but not quite sure if this is really the reason.