[Aegon the Unworthy]

Actually Kingslayer is correct there Boazie....Tyrion was convicted for killing a king after all.

I think Bronns actions you mentioned (saying regicide in front of Varys and standing in open contempt of Cersei) can best be attributed to his arrogance. He was arrogant you know. His actions at Castle Stokeworth are easily explained as being his only possible course. Cersei sent someone to kill him, that person failed, he chooses not to run immediately because that option is open to him anytime. So he mocks Cersei with his castle full of loyal retainers. He can run whenever opposition is arrayed against him, until then live a little. Hadnt Tywin taken a crossbow bolt to his "Little Lion" at that point anyhow?

Shae with the necklace is curious. But the fact that Tywin took her to bed anyhow shows that public and private Tywin were two different people. In fact I would go so far as to say that Tywin is exactly like everyone who ever publicly abhorred the way his parents raised him and then found himself being the exact same way as they got older.

Now that Ive addressed the majority of your points (Ill leave out the "Spy wouldnt rat out incestous twins" line because I think thats ridiculous). Tywin didnt spy on Tyrion because he didnt have much respect for him. Oh sure he felt Tyrion had a little low cunning but at the end of the day he felt Tyrion was inconsequential. Tyrions entire goal was to prove that wrong.