Since it keeps coming up, I looked at my copy of the AiA ethics statement. It contains "canons" (i.e. broad principles) and then rules.
In the area of obligations to the profession, it notes:
E.S. 5.3 Professional Recognition: Members should build their professional reputation on the merits of their own service and performance and should recognize and give credit to others for the professional work they have performed. Rule Members shall recognize and 5.301 respect the professional contributions of their employees, employers, professional colleagues, and business associates.
I.e., don't sell by badmouthing others.....which rarely works, although we do have a great example of how it has worked right here on this forum!
Also of interest, this clause appears to cover obligations of an architect with the task to make decisions on conflicts. In ASGCA, this also applies to settling disputes between contractor and owner as the project architect, but this could apply if an owner asked for a second opinion. Basically, be honest in your opinion even if it differs with the owner who is paying you.
When acting by agreement of the 3.202 parties as the independent interpreter of building contract documents and the judge of contract performance, Members shall render decisions impartially.