Debs is a needy self obsessed bitch. Everything, EVERYTHING, is about her. No matter what the situation it always comes back to her.
The foul mouth is a typical cop show affectation to make the character seem tough...it just comes off as really weak. She has as much credibility as Michael Jackson singing 'I'm Bad, I'm bad...'. Oh stop it Michael, thats scary.
Jennifer Carpenter does a great job making the character so appalling.