Hello Sonialuo...
I agree that, while there is close connection between the "code of ethics" and a series of not too complicated questions for forklift end-user/possible purchasers, it maybe better to split into separate (and overlapping) conversations.
I also agree that anyone could -say- they follow any code of ethics, [Kind of like how I insist that no employee use the phrase "to tell you the truth", since that phrase indicates there are times when -truth- is not being told] in the USA {at least, and most likely any place that wants to have integrity in their marketplace}, if you advertise you do something, and then fall to live up to that advertising, there can be serious repercussions.
As I see it, the series of questions should be more important than the "code of ethics", (and important to keep brief and simple), as the answers should tell more about about the ethics than asking someone if they are honest, since everyone would -claim- to be honest.
I also agree with forklifter that part and parcel to either, [and inclusion by reference in both is a 'must'] that some clearly defined terms to reduce ambiguity in sales would be a good starting place.
what is "rental ready". what is "safe and serviceable", what is "retail ready", and how they differ. I think an open source/ creative commons type license, usable by everyone for free universal outline for a used truck condition report should be pretty easy as the start point.