When you engage with a pay-for-performance marketing or sales vendor, you have to ask yourself: How many other deals have they accepted?
If yours is the only one, you have to wonder what kind of business model they have that puts all their eggs in your one basket. And if not, you have to wonder just how much time they're really going to put into you.
The real problem, of course, is that, despite what they tell you, they don't believe in you. They have no idea if your product will sell. And they don't even care. Why should they? They just take every gig that's offered, and if they happen to trip over an opportunity, they'll be happy to put it through.
But if you think they're going to invest their money in your dream, you're delusional.
You get what you pay for.