I just binged seasons 1-3 and also just joined the sub, so I apologize if this is repetitive, but I am so annoyed by this character right now. I'm starting the 4th season now and am at the point where Acosta steals the ambulance to drive in loops.
Obviously there are other examples of her being extremely unlikeable, but going on a rant about how she's a good person, and is probably the only good person in the town since she's the only one who hasn't resigned herself to being stuck, just to then immediately ignore a distressed boy on the side of the road, whom she knows to be an actual member of the community? I haven't been that annoyed by a fictional character since my last rewatch of The Walking Dead.
Not to mention her rant to Boyd about how she's a "good cop," just to then very shortly afterwards point her weapon at the town's only doctor, whom she knows is only there to try and help. At least the town's other characters who make horrible decisions are driven by a desire to help others, or some sort of manipulation, but she's completely driven by fear, ego, anger, and a desire to help herself.
Even before she becomes aware of the monsters and the town, the first thing she does is handcuff an injured woman to a wall for trying to warn them, and then abandon her. And not once have I seen her show any remorse or accountability for that. She states she's sorry for what happened after, but never seems to mean it, especially since her apologizes always come paired with justifications and another ego trip.
Even if they try to write a redemption arc for her, they've made her so unlikeable that I'm not sure I'll be able to buy it. I can only imagine at this point that her role is to sow chaos, and then hopefully die a Dale-like death.