As both an anthropologist by training and a former Peace Corps volunteer, I am familiar with culture shock. I have lived abroad, traveled and/or studied for periods of up to two years, on three continents. In adjusting to a foreign culture, you expect to find differences--sometimes very hard to adjust to--but you think that coming home will be easier.
Reverse culture shock is more of a shock to my system than culture shock. Nothing has ever struck me quite as strongly as my inability to choose a box of cereal in the cereal aisle, after returning from two years in Morocco (and two choices of cereal). However, the emotions I experience upon reentry from Buenos Aires almost rival that feeling of disorientation.
Each time I come back from Buenos Aires, I have a period of time when I need to re-adjust to my home tango culture of Portland, Oregon. I am used to cabeceo, and I feel a mental jolt to have someone walk up and ask me to dance verbally, even though I occasionally do the same thing after a prolonged absence from Argentina. Also, I get used to the high level of musicality I find in Buenos Aires, even if the technique level is not terribly higher than in Portland. I expect a more relaxed body contact and more energy exchange when I come home, and often feel frustrated by the North American focus on "steps" instead. I become accustomed to small steps and no room, and have to mentally adjust to the more globe-trotting Portland dancer who sometimes does multiple laps of the room during a tanda.
I call this period of time "the Buenos Aires letdown" and spend a lot of time griping about being back for a few weeks. When I go dancing, I experience a sense of withdrawal from a drug, a craving for high intensity tango in Buenos Aires, my favorite addiction. Gradually, I remember why I dance in Portland (to see friends, to relax, etc.) and rejoin the community mentally.
But those first few weeks are hell.