Conversations have pointed out that Allison tends to be a little "blunt" and "hot tempered" with others. So, while I think that the shown Charisma is a bit low (would go with 5 instead of a 4), you can see how the "hot tempered and in your face blunt attitude' can detract from her overall Charisma rating. I just think that it should be +1 due to her LOOKS making people tend to either forget how she can be, or underestimate her ability to call you out on you own BS.
I mean, let's be honest. We all can name one or two people who we looked at and went "wow", only to turn around and go "no way in hell" after spending time with them and their attitude annoys you. Not to mention that she is in a "position of authority" at work, so she is probably a bit more used to "bossing people" than most people are. Which obviously impacts her Charisma as well.
I like Allison (A LOT), but I honestly can't really imagine her as someone who would be able to "talk me into something" that much. Order me to do it? Yes. I can see her also being a "little" willing to "tease" to get her way without a "payoff down the road" (Minor cock-tease) at work, and probably in a relationship. Passionate, but only AFTER you get past her barriers she has up due to work environment. She only really "unwinds" with a select few OUTSIDE of work, so you don't get to see the "real" her that often if you only know her in general.