On contrare, the darker the oil the more fine wear particles or contaminants it contains.
Not true in any manner that can be objectively measured.
Oils have dyes; that's what gives them color.
Particulates alter the color, but the insolubles and soot cannot be measured via the naked eye with any credibility.
Moisture alters the color, as does fuel content, etc.
Further, even if the oil is "darker", there's ZERO indication if the oil is suitable for use or not. You cannot ascertain fuel dilution, soot loading, insoluble counts, silica, etc from a naked eye analysis of color. And, even if you could quantify the color (which you can't), how would you know which contributors were present or absent?
Wanna know if the oil is suitable for use? Get a Used Oil Analysis, not a paper towel analysis.