Ujm, daas – I can’t say with certainty, but the following might shed some light on it. I asked rav belsky once about rav elyashiv’s name appearing on the kol koreh, and he replied by saying that rav elyashiv’s wording of “if it’s what you say, then it is assur” implies that he did not believe the metzius to be what the Osrim were claiming, and that this statement was in fact a subtle way of saying that he did not believe it to be so. when I asked him about a different rov who i held in high esteem, he “mached avek” but didn’t insult him sharply either. My guess is that he would have said that rav dovid was misinformed.
I honestly can’t say with my own aidus that they are visible without a background, because even with glasses I have somewhat poor vision. I am merely relating what he said at the time. Have you examined clear water and seen them, after removing them and verifying with a magnifying glass that they are indees cope pods and not lint? Perhaps you are seeing something else?