1. Rav Amiel has an interesting insight in his Higyonot El Ami. Pre-Parshas Lech Lecha, human beings were called "basar," flesh, as in "Keitz kol basar ba lifanei...," or "Lo yadon ruchi b'adam b'shagam hu basar." Things change in Parshas Lech Lecha. In referring to the people Avraham converted to his cause, the Torah uses the expression, "Es hanefesh asher asu," the souls which Avraham made. Avraham taught that a human being is not just an animated slab of meat, but is a spiritual creature. Not only did Avraham's attitude impact those close to him, but it even had an effect on the King of Sdom, who begs Avraham after the war against the four kings, "Tein li ha'nefesh," let me keep the souls that live in my city even if you choose to take all the property.
2. Avraham refused to take anything from the spoils of war lest that give the King of Sdom the opportunity to say, "Ani he'esharti es Avraham," I made Avraham rich. What kind of crazy hava amina claim is that to be worried about? Surely everybody knew that Sdom and his compatriots had lost the original war, and if not for Avraham's intercession, they would have been wiped out. The King of Sdom himself was almost killed in the battle and escaped only by virtue of a miracle. He admitted that he deserved nothing and would have been happy to get back his people alone.
It could be that the lesson here is that kiddush Hashem in the fullest sense is only when something cannot be questioned even by the most biased observer. A kiddush Hashem in the fullest sense is not when it's lauded in the Wall Street Journal; it's when it's lauded in the NY Times. Avraham wanted to pass the sniff test of even those with the most warped sense of justice (see R' Y. L. Chasman in Ohr Yahel).
It could also be that the word, "he'esharti" has nothing to do with the money. Avraham was not afraid of being accused of growing rich off Sdom; he was afraid of being accused of being enriched by Sdom. Avraham was the paragon of chessed, yet he found himself enmeshed in war. He could hear the voice of Sdom whispering in his ear that chessed may be nice, but sometimes you need to compromise a little -- war means fighting, looting, pillaging, not playing nice. Of course, Avraham would always be Avraham, but maybe there was just a little truth to that voice in his ear? Avraham said no -- he would fight, but he would not benefit from battle; he would not even in war become to the slightest degree influenced by the thinking and methods of Sdom (Shem m'Shmuel).