what the heck is Polarization anyway?

[godwide_void]

I'd say you answered your own question:

in my own life, I might think STS thoughts, but I don't believe that this increases STS Polarization. I think polarization entails more than just thoughts, it means taking successful ACTION based on those thoughts.

would this be fair to say, that:

a STO/STS thought + a successful action based on that thought = increase in polarization

I used to think that thoughts themselves added or subtracted to polarization before, and did well to 'guard the sense doors' and always tried to prevent unwholesome, unskillful, negative states of mind from arising, erase them if they did, and trying to avoid dwelling on them for too long.

If simply having a thought arise determined you increase in STS/STO that would be pretty messed up. No, it rests on the deeds you perform and the words you utter; before either can be done, your volition (intention behind actions) and initial thought needs to be in order. Contemplating upon negativity and understanding it allows you to recognize why it shouldn't be acted upon and its polar opposite. By doing this you prevent yourself from acting from an unskillful place and subsequently, STS polarization becomes close to impossible (assuming STO is what you wish to refine yourself in).

We're all still human and are still prone to thoughts and emotions beyond love, even if that may be our prime focus. Just by making the effort to correct our thoughts and intentions so our words and deeds may be reflective of your desire to become more positive I would believe that you are making progress, and just from the attempt at that.