Just remember this the next time you sit down to negotiate a contract: If you don't ask, they won't tell. Sales managers are trained to answer only what you ask them — they won't volunteer information, especially if it might cost them something. If you ask about any additional fees, for example, the sales manager may point out the fees relevant to your meeting, but not necessarily any additional house surcharges. Why not? Well, you didn't ask about those.
So how do you determine the r