My rooster has the same thing and I also was wondering what it could be. The dark spot is at the base of his very large comb. The tips are not frostbitten so I ruled that out.
I have been wondering the same thing. This past summer I hatched 2 chicks in an incubator that were both males and then I had a hen hatch out 3 and they turned out to be all roosters also. What are the chances?