John, you wrote "All ad hominems are red herrings but not all red herrings are ad hominem." In fact, both of these are examples of informal fallacies, but they are different animals. A red herring is a fallacy that occurs when the arguer divert the attention of the reader or listener by addressing a number of extraneous issues and ends by presuming that some conclusion has been established. (It comes from a procedure used to train hunting dogs to follow a scent. A red herring (or bag of them) is dragged across the trail with the aim of leading the animal astray. Red herrings have an especially potent scent, caused in part by the smoking process used to preserve them.)
Again, thanks to Hurley.
Blues