I've been noticing some of the combs on my roosters have black spots as seen in this picture. What is it? Should I be alarmed?
It could be dry fowl pox, and no, it's not serious. It's a virus carried by mosquitoes. It will hang around for 3 weeks then disappear, and those chickens will then be immune to it for life. Occasionally a bird will get infected in the mouth, which is then wet pos, and that can be serious and requires some treatment. It could also be a peck park, a scab.
Prolly fowl pox just let it run it's course of a couple weeks and it's prolly gonna look a lot worse than that
Those look more like peck marks than Fowl Pox, to me. If the scabs get larger or become more numberous, it's probably Fowl Pox. Whether they are scabs or Fowl Pox, it isn't too much to worry about. Scabs should go away in a week or so. Fowl Pox lasts for up to 6 weeks or so, and is rarely fatal, unless it turns into the wet form (which invades the throat).
Peck marks is what it looks like to me. They are usually small and jet black--if you see them before dying they will be bloody. Fowl pox usually is tan with a dark brown scab. those can also be bloody at first when just bitten by a mosquito. This link shows the usual scabs of pox: https://www.backyardchickens.com/a/avian-pox-how-to-treat-your-chickens-for-avian-pox