I didn't take it exactly the same way. I thought that she was trying to be excruciatingly honest, and could not say absolutely that she couldn't have possibly blacked out. (After all, how would you remember if you blacked out? That's the whole problem with blacking out - you do things that you later have no memory of.) I also took it the same way about her checking on the baby at 10:30. I "read" her answer as being that she may not remember doing it specifically, but knows that she normally does. If she did, then surely she would have seen IF Lisa was missing at that time. But since she doesn't specifically remember looking in, it's possible she didn't.
That was just my own impression when I first saw it, and honestly, I was really confused when people started picking that to pieces. It just seemed so understandable, lol. I know NOW why everyone didn't see it that way but it still seems like maybe half of us interpreted it that way and the other half saw it completely differently.
By the way It's not just alcohol that can make people "forget" doing things, especially things that we do out of habit. Most people would not be able to say exactly what they did the night before. They would remember much of it, but like EXACTLY what time did you start cooking dinner? Do you remember putting a specific paper towel in the trash? Do you remember brushing your teeth? You know you did it because you always do, but do you recall the actual act of it? I have said goodnight to my daughter before, and then been surprised to find that she went to bed. Even when my hubby reminds me that I said goodnight to her, I can't really remember it. I believe that is normal, so I never thought it was particularly weird that DB didn't remember the actual act of looking at her baby. The brain can't remember every single detail, and once something leaves the working memory, if it doesn't go into LTM, it's gone. And no amount of thinking will get it back. IF she is innocent, and IF she is telling the truth, she would have had no reason for remembering that act (looking at Lisa), if there was nothing wrong at that time.