The agreement maxim
I find the agreement maxim interesting. This maxim is (at times) is basically just a lie. The agreement maxim says we should minimize disagreement and maximize agreement with the hearer. So let's pretend someone gives me an idea. I reply with "I think that's a good idea, but what do you think of this..." Basically what we often mean with a response like this is "I think your idea sucks and mine is better." I wonder how many friends we would keep if we just stopped following the politeness principle all together.

Comments
It's a rare person who desires the truth from another person and not just their own opinions spouted back at them.