Why did Vito ask Luca Brasi to pose as an informant to find out what he could about Sollozzo and the Tattaglia family? Wouldn't he be the worst possible candidate for a mission like this? They'd have to be unbelievably stupid to believe that Luca, the Corleone's most fanatical devotee for decades, would suddenly be so discontented that he would switch sides. Why not send a more "average" soldier or associate instead?

Let me tell ya somethin my kraut mick friend!