Hard to say. I never noticed them at all. Adam came by and he saw them. I think they show up easier on fading or bleached corals due to red on a light background. I agree, some of my nicest pieces are covered and show no problems. In fact, one humilis I have has started growing faster since getting them!!
The problem is adding a new frag...will it tolerate the bugs, or shrivel and die? Expensive gambling habit
BTW, the coral I dipped has fully recovered (from the iodine) by this morning and all it's polyps were extended.