I believe that all posters in the cause of honesty should declare their interest when making a point.
If an American or Brazilian,whatever for example posted that the British Armed forces were wonderful, the message would come from a degree of impartiality and from a degree of a not so close up viewpoint.
If however the post was made by myself then there would obviously be more then a degree of partiality being a Brit.and coming from a military background.
Many regular posters backgrounds ,whether friend or sparring partner are known to most of us but quite often there are posts on contentious issues that are vague on the posters location,credo etc. where by default we usually believe them to be American .
Is the post condemning the U.S. presence in Iraq from a concerned American or from a Pan Arab?
Is the post villifying Hamas from a European or from an Israeli?
Well thats it really but I do feel very strongly about this personally as part of objective free speech.