i think those look fine, not totally sure what exactly you are worried about, but i see nothing that would concern me.
sometimes, when i move the cacti, or maybe if theres a strong wind, the cacti will bump into each other, and the spines of one cactus will poke into another. if the spine breaks the through the epidermis, it usually scars over with a small black spot. guess it could be from bugs too, i have had slugs do some damage. a similar thing happens if they experience sunburn or other stress damage, except the scar is usually lighter in color, grey or tan. all of these seem mostly superficial.
are the black spots squishy? do they appear to be rotting? if so, then i would be concerned...