I absolutely and TOTALLY agree that noise generators are muck--- no, *ucking up the AM band! In my opinion, the part 15 rules need a serious overhaul and enforcement.
For intentional radiators, I think the rules should be relaxed some - for example, allow 1 watt input to a 25 meter antenna, not counting the transmission line or ground lead, for AM broadcast, and maybe 10mV/m at 30 meters for FM, for example. However, for unintentional / incidental radiators (the noisemakers), in my opinion, when you measure at the INSIDE surface of the device (for example, the inside of the cover on a computer power supply, or the inside of the insulation on a cable), the maximum field strength should be something like at least 120dB BELOW atmospheric, galactic, or whatever is the lowest level naturally-occurring noise. Or, if 120dB isn't the proper number, whatever would be such a level so that if the "natural noise" was represented by an unmodulated carrier of some sort, and the "noisemaker" was represented by a 125% or more modulated QRSS CW carrier with a bandwidth in single-digit Hz, it should be impossible to detect any trace of the "noisemaker" even with the best equipment, when measured at the inside of the noise source chassis.
In my opinion, just solving the rampant noise ALONE (nevermind IBOC, although that's a huge problem too) would go a LONG way to cleaning up the AM band.