I think some people's 'normal' isn't necessarily feeling 'good.' It could be mild depression, for example... Or one's normal could be high energy and not needing a whole lot of sleep. For some, it will basically be 'content.' it just depends on what kind of person you are and the gamut is endless. Bipolar is always about extremes.

I know for me it's constant, unrelenting anxiety (which disappears when hypo) and relatively low energy (which disappears when hypo). Depression is never my baseline, I'm not depressed unless in an episode. My constant companion these days is anxiety and the rest are episodes, luckily few and far between at this point in my life; I finally found the right combination of meds for me.