I don't find the "I can trust them because I'm paying them" idea very useful. Nor the "If you're not the customer you're the product."

The bottom line is, if your information is valuable, then it will be in the advantage of those who possess it to exploit it whether you pay them or not. The only real non-moralistic consideration is whether you will stop paying if they start selling.

Either way, "I have a moral obligation to not sell your info, even if you don't pay me not to" sounds a lot better to me than "I don't sell your info because you think you're paying me not to." It's a horse apiece if you're dealing with strangers and you have to take them at their word.