What is the halacha regarding bruises commonly found in poultry sold in supermarkets and butchers (of course, with a reliable hechsher)? Since no incision is found near the bruise should it be cut out – as written in Shulchan Aruch. This is a common occurrence which gives the impression that if it were a problem the hashgacha would not allow it, or perhaps the hashgacha assumes that the consumer knows to remove the bruise.
A red color in the skin does not usually indicate actual blood, rather fats or juices, and does not need to be removed. Rarely, there is actual blood caught under the skin from an injury to the chicken. More scrupulous kashrus agencies actually have someone checking chickens to remove these spots, but they don’t catch every one. The blood should be removed with a small amount of chicken surrounding it. But again this is only when actual blood is found stuck under the skin and not just red coloration.
See Shulchan Aruch Y:D 67:4, there the Shulchan Aruch refers to removing the blood before salting. If the chicken was already salted the entire spot and a little around it need to be removed, see Shulchan Aruch Y:D 105:9, 21:1, 72:2.