Quote Originally Posted by PseRamesses
Despicable
Very untrustworthy
Untrustworthy
Mixed
Amiable
Good
Trustworthy
Very Trustworty
Reliable
Very Reliable
Immaculate
(Did I miss any?)
The above is actually a mix of "Reputation" and "Relations" grades. Amiable comes from the "Relations" category. Not sure where despicable comes from.

My shot for the top end "Reputation" grades:

...
Mixed
Reliable
Very Reliable
Trustworthy

Sorry, cannot recall the "low end" right now.

On another note, Mushashi here suggests forming alliances with every faction at the beginning of the game. This backfires in midgame since for every alliance you break due to choosing sides (when one of your AI allies attacks another) there is a hit to your reputation. The hit appears to come regardless of whether one chooses to remain allies with the attacker or the defender...