Their incentives cannot be completely aligned by definition. One views you instrumentally, the other doesn't. But it can be difficult to tell because, as you point out, there can be some alignment and even some truth in the advice of persons who want to exploit your ability. This is why I suggest erring toward taking advice from the dead. This has the virtue of being the most disinterested advice. It takes experience to follow advice from the living. Most of this is noise. Look for alignment with the advice of the dead, especially if this has withstood the test of time. You should note that my attempt to defend my advice from criticism is already validating my thesis, which is that you should not take my advice until after I am dead, and that goes double for my contemporaries.
But by definition when the dead gave their advice they were alive. Just because they're dead doesn't mean that their advice doesn't serve a purpose for them or for people like them. Wouldn't you run into the same issue? You never have a total vacuum.
How do you know there is any conflict if they are advancing their own ends within their own group? I'm not religious--I don't believe in general ethical principles either. I'm a particularist. If I were a consistent particularist, I wouldn't advance the general principle not to listen to advice from anyone who has an interest in giving it. I would suggest asking if they were disinterested or not, and to what extent. It's my observation that most of the advice one receives isn't disinterested--but I could be mistaken. For that reason, I have a preference for the advice of the dead, but certainly not all advice they have to give, and mostly for the moral lessons of art and literature--not necessarily explicit guides to conduct.
As a particularist, I would avoid following general principles of conduct in every case, since these do not work in the generality they claim. While I might prefer to use art, literature and religion as a guide to some aspects of conduct in particular cases, I would avoid following to the letter any express or implied general principles of conduct they might contain. With respect to your article, as far as religious texts go, there is Ecclesiastes 9:11.