"Bad Girl" is my favourite track on SNSD's Japanese album, and (I'll say this on TSJ as well) I think you get a lot more out of it when you stop looking for "strength" or "badness" and accept that SNSD really have only two modes: "adorable" or aegyo, and "arrogant", which covers what other groups would interpret as "sexy", "bad", "I Am The Best", etc. They can't be real "bad (http://www.youtube.com/watch?v=gGN_W4VBZFo) girls" (http://www.youtube.com/watch?v=tAzNHVBVh7o), so instead the song lets them be haughty, which they can do (and well).

To illustrate their two sides, the ending of the video for "Oh!", in which the kanpeki na bad girls of "Run Devil Run" (arrogant SNSD) tear apart the clubhouse of the cute cheerleaders (adorable SNSD). They're good bad, but they're not evil: