I sell cars for a living, I would never perform a related mystery shop even if I changed professions.
As for your potential report, the company may see everything as being by their way of doing business.
I work for a posted price dealer, I can provide a quote at any time, we do not negotiate. For appraisals, I return customers keys before presenting the numbers.
As for stating you can pay cash, unless that's part of the guidelines I would not include such verbiage. Dealers make money by arranging financing. Your lowball quote will be higher than for someone needing to finance. Keep it simple, you plan to cover all the tax, tags and fees, will finance the rest. That's if your guidelines allow this.
If anyone is actually looking to buy a car, you can PM me for some basic advice for today's environment, not the outdated stuff rehashed by the major portals from 30 years ago.
My posts are solely based on my opinions and for my entertainment, contact a professional if you need real advice.
When you get in debt you become a slave. - Andrew Jackson