My chickens are always finding ways to get tiny nicks and scratches in their combs, especially the rooster. They look like tiny black dots-- the scabs do, that is. They are often in a line, as with a scratch! Let me see if I have any photos of it on my birds. I'll edit my post if I do...
They look different than avian pox: not as large, no inflammation or swelling, no pus, no change in texture, etc.
EDIT:
Okay, found a few photos. Not the best examples, but it's what I have! My chickens like to walk around in the berry brush...
Because of the texture of their combs, as clearly seen here... which is bumpy and pebbly, any cuts or scrapes they get tend to skip along the 'pebbles' and create series of scab dots, instead of a long scratch like we'd get on our skin.
You can see the black dots, which are little scabs. They often heal and fall off within a day or three!
A few little scabs on Moa's comb:
And a few on Chickadee (note the tip of one of her spikes, and down closer to her beak and nostrils is a larger scab):
I hope this helps!