|They wear G-strings to war|
The "Gaijin Nod" does usually not extend to tourists (and it's fairly easy to see who's a tourist and who's a resident foreigner) and does not really exist as a real phenomena in the Tokyo area due to the comparatively large amount of foreigners.
It seems like some foreign residents here in Japan embrace the habit and give the Gaijin Nod enthusiastically, but quite a few people take the opposite stance and deliberately out of their way to look the other way to avoid having to acknowledge the other foreigner.
So yeah, conceptually, I'm quite ok with the Gaijin Nod but felt more or less forced to stop with it and now, living in Tokyo it's no longer any issue. A complicated topic indeed...