I’m currently using a series of bools to track my characters mood, example:
Really Bad Mood
Bad Mood
Neutral
Good Mood
Really Good Mood
I’m wondering if there is perhaps a more elegant way to do this as I sometimes need to figure out if my character say had a good time at the party by not only just their current mood but what their overall mood was during the time they were at the party.
Not sure if that makes sense? But if you need more clarification just let me know. 
First, if your just going to condense your “mood” calculation to a single variable, a float range or at the very least, a single enumerated type might be a better choice.
I thought your question was interesting, so I asked my wife who is a social psychology professor that studies mood if there are “standard” scales. She says there are, but they are hotly debated and most researchers create (or use) a scales centered around the affect in which they’re interested. PANAS and Core Affect scales are two examples.
In your party example, an approach may be to break your characters affect into a collection of (weighted) motivations and then deriving a mood value from the integration over time and summation of how well those motivations were satisfied. For instance, hunger, thirst, social interaction, entertainment, etc. Each would likely be affected by time and access to a mitigating source (food, drink, people, music ), and the quality of the source (good vs. bad food, engaging vs. boring people).
Mike