"I'm not the easiest person to live with. I'm kind of a slob"

Katie Holmes is most likely describing her own personal routines and how they might not be the most preferable to deal with. She is likely referring to her own messiness and lack of company, which can be hard for others to cope with. She is likely knowledgeable about her own imperfections and is being sincere about them. It is most likely that she is not the most organized person and her living space might be jumbled and disorganized. She might also be describing her own habits and how they may not be the most preferable to deal with. She might be describing her own lack of tidiness, her propensity to procrastinate, or her lack of company. Whatever the case, Katie Holmes is being honest about her own drawbacks and is most likely aware of how her practices might not be the most preferable to live with.