Here are some measurements of local mains, done with Agilent MSO6034A and Fluke DP120 CATIII differential probe. Time- and frequency domains are in separate pictures to get better views in each domains.
It seems that 5th harmonic is dominant here, but mains is still relatively clean. Not as clean as in PowerWare 9120 online UPS I have, though.
One can reduce the mains pollution by preferring equipment which has power factor corrector, as that will make the input current more sinusoidal, thus creating less distortion. Distortion problem is worse on those countries which use lower mains voltage, since currents are higher.
I think that if the power distribution would be invented today, DC would be much better choice since most equipment runs with DC anyway, and polyphase AC motors could be fed with the VFD. With DC, there would not be distortion problems, and no AC losses on the distribution networks, although that would make voltage transform a bit more difficult, but I think that would still be solvable problem using today's technology.
Regards,
Janne