x2If you have a picture of him, we may be able to help out and identify some breeds. Most breeds have a certain dominant trait or two that you can pick up on even in mixed breed chickens.
Pure bred birds will look like a standard, which is described in the Poultry Standard of Perfection. Though sometimes it can be more difficult to tell if the bird is not great quality. I often have a difficult time telling what breed hatchery birds are, because many of them just do not fit the breed standard. For example, I have a partridge cochin hen that looks more like a partridge brahma. In that case it can be hard to tell if your bird is purebred and just poor quality, or if there is some other breed mixed in.
Pictures definitely help though!