It was a soft, purring voice - a voice used deliberately as an instrument - nothing impulsive or un-premeditated about it.
Mr Shaitana carefully cultivates an image of devilish mystery, enjoying the fact that he can be somewhat frightening to people, and his voice has been carefully cultivated to fit this image too. He is also aware that the way in which something is said can be even more important than its content, using his voice to insinuate, cajole and otherwise manipulate those he wishes to comply with his goal.
Shaitana was a man of great vanity. He was also a stupid man. That is why he is dead.
Shaitana's vanity led him to create a dinner party for the purpose of proving his own superior cleverness to his guests. His vanity meant he wanted to prove to his crime solving guests that he had greater skills as a detective than they did; it also inspired him to torment the four guests he "knew" to be murderers and dangle a quartet if famous detectives in front of them. However this great vanity prevented him from considering that they might try to kill him to prevent their secret from coming to light, assuming he could outwit them before such a thing could happen.
To tell you the truth, a real murder has never come my way before. And to continue telling the truth, I don't believe a real murder is very much in my line. I'm so used to loading the dice.
Mrs Oliver is a crime novel list and by her own admission uses the same plot repeatedly in different situations, usually resorting to untraceable poisons as her fictional killers' weapon of choice. She is a brilliant solver of crimes when she is the one who has created the crime in the first place but is rather out of her depth when it comes to a plot she has not created in the first place. This is somewhat ironic when it is Rhoda's conversation with her that enables Poirot to crack the case.
I expect he has been quite good in his day. He's gaga now of course. He must be at least sixty.
Because Poirot gives the impression of being eccentric and peculiar, as well as his propensity to go off on seemingly unrelated tangents, both Rhoda and Anne underestimate him an his crime solving ability. Believing him to be over the hill Anne does not try to harm him and Rhoda is open with him believing it doesn't matter what they say since he is no longer up to solving the crimes anyway. This is an impression Poirot gives in most of the novels he is the protagonist in.
Luck? Luck? That was not luck Mademoiselle. That was the grey cells of Hercule Poirot.
Rhoda comments that the murder being witnessed by a window cleaner was a lucky break for the investigators, not realizing that the window cleaner was in fact a friend if Poirot and the entire eye witness story was an elaborate bluff to secure a confession. Poirot is proud of his little gray cells and his reference to them in every Poirot novel is similar to his catchphrase. He has such superior detective skills that he already deduced Dr Roberts was the murderer before he struck, proving why he had acquired such a formidable reputatio.
