Here's some neat info for the Trailhead:

Chapter One
Identifying the Mark Trail Bad Guy
This is one of the first skills a neophyte Trailhead should master. When you have learned several of the following rules, you will be able to tell at a glance if a new character is a shyster or a saint. Take a look at the fellow on our right. His name is Ted Baker and he's a banker. He's also a bad guy who Mark Trail eventually knocked out with one punch. Baker is serving a 20 year sentence. One giveaway that a character is evil is by his facial hair.

Bad Guy Rule # 1--If a character has long sideburns, he is always evil to the core.

One should be suspicious of a character with any facial hair; in the case of characters such as Joe Walker (see the Sea Turtle episode), he had a very thin mustache, it gave us the hint that he had a dark side but was probably not rotten through and through. In judging characters with facial hair other than sideburns, one must take into account their general countenance. Bad guys are often mean looking and they rarely smile.

Bad Guy Rule # 2--Men with hair any longer than collar length are bad news.

However, boys with longish hair may be merely impish, such as the character Joseph in Andy's Great Woods Adventure (see Trail Archives). Mr. Elrod appeared to bend the hair rules in May '02. Mark's swamp buddy, Gator, has a tremendous head of hair reaching to his shoulders, as well as a full beard. Argument on the Mark Trail Bulletin Board concerning this incongruity is generally of the opinion that Gator's hair is snow white, implying his good character. I would point out that the colorizing of the online strip is apparently computer generated, and not under Jack Elrod's control; Gator's true hair color may or may not be white. Mark, upon meeting Gator, immediately pointed out that his friend needed a haircut. This suggests that all male long hair is still bad news. Gator may be a Good Guy, but he appears to have a fascination with the Dark Side of Life. Mark realizes this with the gentle rebuke of his fragile friend.

Bad Guy Rule # 3--Any character, even if innocuous in appearance, is suspect if they hesitate when responding to a legitimate question.

A good example of this is to be found in the Sea Turtle episode, as Mark questions Mary Moore's lawyer, who responds with an "Uh..." before answering the question. Any utterance beginning with "Uh..." indicates deception or embarrassment.

Bad Guy Rule # 4--Unless smiling and of a friendly visage, Heavy-Set Bald Guys are always villains.

Any gang of drug smugglers may include one (and only one) Heavy-Set Bald Guy. These Bald Guys are always completely bald; you'll never see one with lingering hair around the ears or a mere bald spot. Trailhead Erik Biever pointed out this Bad Guy Tipoff to me, and he notes that totally bald Bad Guys are never skinny. The Bald Bad Guy may sport facial hair or oversized eyebrows, but not a hair is to be seen elsewhere.

Bad Guy Rule # 5--Bad guys often have bent or broken noses.

This may be because Elrod keeps calling the same characters up to be bad guys, and their noses have already been squashed by Mark, who knocked them out with just one punch in some previous adventure.