I don't think manufacturer list contrast ratio anyway they want (maybe only salesmen can do that, hehe). I don't how much better a 4000:1 screen is to the 1000:1 screen but I think the issue is that your friend didn't get what he ordered and he certainly has the right to return it if he so choose. But before he do that, he should compare the 2 screens, maybe he might be really getting a better screen as the salesman claimed (but I have my own thought on that). Just my 2 cents.
Recently, a friend of mine purchased a 42" Electrograph EDTV Plasma after having been told by the salesman that his intial choice, the Samsung (model #SPN4235) 42" plasma, is old and has a lot of problems (don't know the model name for Electrograph but around the $2,000-$2,500 range). The Electrograph is listed as having a 4000:1 contrast ratio. The store then decides to ship a Maxent plasma screen around the same price range. I call the store for my friend to find out the differences and the Maxent is listed as having a 1000:1 contrast ratio. I ask for the right plasma screen to be shipped and he begins to explain to me that contrast ratio is always wrong and Electrograph and Panasonic both use different measuring numbers than other companies. While I believe numbers may be off, I dont believe you can lie so much to where it becomes false advertising. The Electrograph had 4000:1 contrast ratio and 780 cd/m2 compared to 700 for the Maxent and the salesman tells me its the same plasma and the Maxent is actually better and more expensive. Is he getting ripped off from the store (the store basically chose the plasma tv for him), or can manufacturers list contrast ratio however they please? I have never heard about using different tests for contrast ratio.