Choose any girl in the inventory (favorite), from there you can see if she is happy or angry (and use the arrows to switch between girls) plus, yeah, only 0 mood points = angry. I did a quick check and there is no bug with Mara that if she has mood points she gets angry anyway, only if her mood = 0.
In any case, the mood system is being reworked and in the v16 there will be no more angry girls as that part will be removed.