Your work isn't just writing code and giving code reviews. Actually, your main job is earning money, and in order to do that you need to know who your stakeholders are.
Often, the PM or whoever you think your stakeholder is will just ask the permies whether or not you're any good. So buy the permies coffee and tell them some dirty jokes, because their answer is going to be coloured by how much they like you.
Being "polite" isn't good enough.