For seminars and visits to other dojos, I wear a white belt. I'm not a member of their organizaton, so I figure that a white belt is the correct rank to wear. Although I've discovered that it's dangerous being a white belt.
When I was in a seminar, I had some yudansha give me this all out attack! I'm wearing a white belt - What's this black belt thinking of? If I really was a beginner, I'd probably be in a hospital. As it was, the black belt just landed with a fierce thump when all that energy rebounded.
Then there are those who decide it would be fun to break your wrist.
A shihan once expelled two members from his dojo and remarked, "Aikido is not about breaking wrists."
Perhaps, this could be a future trend.
So it seems one of the first priorities is to do plenty of wrist stretching exercises, if one wants to survive as a white belt.
Of course, wearing a white belt means that you're basically ignored by everyone ranked above you. Personally I think that's OK since some of the yudansha are outright dangerous to practice with. But I think it strange that the only person in the dojo willing to explain technique is another white belt who started training a day before your visit.
Of course the weirdest character I've encountered as a white belt is the Aikido Mime. They don't speak, they just ssslllooowwwlllyyy go through the motions like Marcel Marceau. You begin to wonder if you're their training partner or their audience.
Thomas Wolfe once wrote "You can't go home again."
Perhaps not, but wearing a white belt reminds you of why you decided to leave in the first place.