Measuring or attempting to measure the DC resistance of a capacitor is a completely pointless and meaningless exercise. A perfect capacitor would have infinite resistance and pass no DC but there is no such thing as a perfect capacitor and they will all have some DC leakage. This may or may not show up as a high resistance reading on a multimeter but tells you nothing about whether the capacitor is good or not. The only way to test for DC leakage in a meaningful way is to apply a DC voltage equal to the rating of the capacitor (which is likely to be 400 - 600v) and measure the current that flows with a micro-ammeter. Paper in oil capacitors are inherently leaky and will always leak more than a plastic film capacitor as paper in oil is actually a very poor dielectric. In the context of a guitar capacitor all of this is completely irrelevant as there is no DC current there anyway!
You say that you have measured the capacitors to ensure they are in tolerance - This makes any comparison meaningless, capacitor tolerances are +/- 20% and any differences you hear WILL be due to differences in value within this range. To be in any way meaningful the capacitors being compared would have to have EXACTLY the same values as measured on an accurate LCR meter.
Anyhow it doesn't seem to matter how many times it is said, some people seem determined to believe the snake oil marketing hype over the facts!
