When episode 3.7 aired (the breakdown in the office), there was a lot of debate among fans about whether or not Jimmy's breakdown and tears were sincere or faked. Him giving that smirk of triumph at the end was enough to convince some that he was faking the whole time.
I was certain that it started as a completely real breakdown and I loved how realistically it played. Stressful incidents had been piling up on Jimmy and the news about his insurance premium was the last straw, finally causing him to break. It's only when he sees the insurance agent take notice of his comment about his sick brother, that a light goes off in his head and he realizes that he has the opportunity to get some payback on Chuck. And you can see it play on Odenkirk's face. There is a moment when he shifts from being genuinely upset, to starting to milk the situation. I thought it was a truly excellent performance.
In any case, I was right. Both writer Thomas Schnauz and Bob Odenkirk confirmed that that's the way it was conceived and played (sincere then fake).
Climbing to a high chamber in a well of houses, he threw himself down in his clothes on a neglected bed, and its pillow was wet with wasted tears. -- A Tale of Two Cities