To my mind, the ambiguity arises from two things Jesus says: "And the master commended that dishonest steward for acting prudently" (v.8a ) and "I tell you, make friends for yourselves with dishonest wealth, so that when it fails, you will be welcomed into eternal dwellings" (v. 9).
Yesterday, a fellow deacon wrote in to let me know that I missed the entire point of the passage and invited me to look at his homily to see how it is done. While I certainly make no claim whatsoever to being a gifted preacher, I am diligent enough to do my homework. So, as to the first point of ambiguity, I will reprise part of my response to the well-intentioned corrective: Jesus does not commend the steward, the steward’s master commends the steward. It seems quite clear that Jesus does not agree with the master's assessment and that he does not approve of the way the steward settles the debts. This is shown by Jesus referring to the steward in verse 8 as "that dishonest steward," as "adikias," meaning, not merely dishonest, but unjust. One peril is to read this parable as an allegory, which it is not. Hence, the master is not God and the steward is not intended to be the listener.
My response to the second ambiguity builds on my first contention. Translated a bit more literally, Jesus says to make friends with mammon. I would prefer that if English translations persist in using mammon in verse 13 (i.e., "You cannot serve both God and mammon"), it should also be used in verse nine in place of "dishonest wealth" because that is what the Greek text uses. Jesus is telling his listeners to handle worldly wealth honestly, which to me is borne out by the fact that he next launches into the necessity of being honest and just even in small things and with what belongs to another over which we have been given charge. In other words, he uses the unjust steward's settling of accounts as an example of how NOT to handle mammon, before commending the steward for a certain shrewdness in looking out for his own welfare. Otherwise, you have created a big theological problem that is quite fundamental, namely that it is okay to act unjustly to secure your eternal salvation!
At the expense of sounding a little snarky, I think we have to be careful not to get too cute with Scripture. Preaching definitely requires shrewdness tempered with prudence, not to mention fidelity to the word. I am unabashedly an expository preacher. I think a good homily always involves some exegesis. I do not like dealing with Jesus' parables by telling a story about a story, which is not to say I think a well-placed story or example has no place in a homily, they certainly do, well-placed and carefully chosen being the keys.