I sometimes DM for a friend who is a skimmer as he reads. He doesn’t seem to be aware that he’s skimming. If when he casts a spell, I ask him to read aloud the text of the spell, he’ll read the first sentence aloud and then sum up what it does the way he remembers it. Then I’ll ask him to please read the entire description aloud.
And then he’ll read the first two sentences, skip a sentence, and then read the last few words of the last sentence.
I’ll tell him he skipped a sentence again, and can he please read each sentence aloud. And then we find out that the spell only works on Beasts and not Aberrations, for example.
He’s a skimmer. And he doesn’t seem to be aware of it. I think he perceives himself as absorbing the full meaning of what his eyes are scanning.