In regards to the relevance of Casey's partying, drinking and general shenanigans, for me personally it is important to separate them into two categories: before Caylee went "missing" and after.
I absolutely think that Casey's activities after Caylee disappeared (was murdered) are relevant. Each and every step she took in those days should be picked apart (IMO).
However, I think it is a slippery slope to judge any mother on their activities prior to an incident (barring a situation where a child is completely uncared for and the mother is neglecting/abusing the child). I say this because, as a mom of 2 wonderful kids, I "routinely" go out with my girlfriends. It's called "Moms Night Out" and just by name alone it implies that all the attendees are moms. Are we scantily clad? Sometimes. Are we drinking? Usually. Are we dancing? Sometimes. But does that make us "bad" mothers? I certainly hope not!
If someone took snapshots of our lives during these MNO events, they would see moms (gasp!) partying. There was even one instance where the bar we were at happened to have an old stripper pole. Needless to say, we took a lot of pics of us being silly on that pole. God help us if someone ever uses those photos to show that any one of us is a bad mom. If someone can show a specific time when a mom (Casey or anyone) was out partying and her child was not cared for, I would think that instance would be relevant. But, if a child is being cared for (by a babysitter, father, etc) then I think moms should be able to have some fun.
Let me be clear: I am not condoning Casey's behavior while Caylee was "missing" and she was "looking" for her. Absolutely not. But, if Casey was wearing a short dress, being drunk and partying prior to Caylee's disappearance AND Caylee was in the hands of a capable adult, then I think her activities (as long as they were all legal) are irrelevant.