I will try to explain myself a bit better. What i found disturbing was, that once you reach a certain level of Itelligence (50), one seems to have reached unlimited wisdom when it comes to identify others no matter what the difference of these two characters is. I find that highly unrealistic and would like to soften these hughe step a bit. What Karyuu wrote ("Currently, the higher your Intelligence is, the better you can estimate someone's strength.") isn't cosequently implemeted - there is only the one mentioned step of INT 50.
So I think what would prevent them of beeing identified would be Itelligence and Charisma. And the best way to implement that could be that a difference is calculated between the values of charisma and itelligence of the character beeing identified and the (_only_ as we discussed) intelligence of the identitifying character. Once the difference is too high - the weaker character shouldn't be able anymore to figure out the others strength.
By the way, why do you have charisma listed twice up there? What's wrong with just multiplying times 2, if you want it to count more?...
uhm - I just wasn't sure how to do that...

"Maybe even when you reach a certain intelligence level you could have the optionr to chose whether to make yourself come over as stronger or weaker than you really are?"
In my opinion this is a great Idea.

Gives more motivation to do train INT.