How do I tell if an AI vendor is selling me snake oil?

A few tells. They lead with the technology instead of your decision. They promise to replace your whole team next quarter, which is mostly people selling shovels. They want a long discovery engagement before they'll build anything real. And they can't tell you, concretely, what you'll have at the end that's worth the money.

So ask for one small working thing in two weeks. Ask what happens if it doesn't work. Ask them to tell you when AI isn't the answer, because the honest ones have a ready list. If every answer is "yes, AI can do that," walk.