A skimmer should skim a nice dark skim, if a skimmer skims wet then it is taking out to much water
A skimmer will just stop skimming when there is nothing to take out.
I can wet skim, but what is the point, I will just end up taking more water out of my tank and the waste will be less concentrated.
Skimmers that are not efficient seem to skim wet. That is what I see when I see the queens, via aqua etc, they all skim wet.