Do we inhabit different parallel universes, Noggin? Or did I just miss a smiley?
My experience of the ADF is that it is a hopelessly flakey navigation system with multiple failure modes that allow single-point failures to cause erroneous readings without any warning at all.
ADFs can easily lose a signal from an NDB, in which case most cockpit equipment gives no alarm signal. Cards can stick to one another as they turn. In 1978 a Cessna 188 got lost over the Pacific when the needle of the ADF indicator became lose on its spindle, and simply pointed wherever it wanted -- the aircraft was saved by an Air NZ crew that located it. ADFs experience erroneous reading around thunderstorms, coastlines and even when pointing towards certain parts of the aircraft in which they are installed, or when the aircraft is in a particular attitude. If a new navigational aid of similar "reliability" were proposed today, it wouldn't clear the first hurdle of a risk assessment.
By contrast, even hand-held GPS units tend to give the pilot an indication of their inability to navigate accurately, though that's not guaranteed without RAIM.
In ClassGMaster's example, the pilot was at least aware that the GPS wasn't working (and there's no excuse for getting yourself into a predicament like that with the failure of any single navigational device). If the authorities were to embrace GPS for the potential aid to safety that it can be, rather than telling pilots of the dreadful disasters that can befall them with this evil device, we might manage to reverse some of the contempt that GA pilots have for the CAA's ability to manage risk on their behalf. The double standards that seem to be applied are transparent to anyone who's been called upon to do a H&S risk assessment for so much as a 3-man office of paperpushers.