Chr, is, unfortunately, a highly overloaded stat with attributes that are often entirely unrelated, or perceptively subjective. It covers everything from the projection of an air of confidence and self-assurance to persuasiveness and leadership ship ability, to physical appearance.
For instance, dwarves are -2 Chr. This suggests that, as a race, dwarves are disunified due to a reduction in leadership, which, of course, makes no sense: Dwarves are a highly ordered lawful society with strong leaders....that have low charisma. Yes, dwarves tend to be cranky, loud, and rude, by human standards, but if the majority of dwarves are that way, then that's something dwarves appreciate, rather than disapprove of....yet the dwarf -Chr penalty affects their relations with other dwarves also. It also negatively affects things like the dwarf's ability to be a paladin, despite the fact that dwarves are certainly not lacking in force of personality. So what if he's disagreeable by human standards? He's a paladin of dwarf god, and shouldn't other dwarves think he's just fine?