Senseis & breeding
Kelly, if the sensei had bred proper respect in them, true most visitors from other dojos would behave themselves.
Occasionaly, however, even despite the sensei's best training students have been known to get "wild" ideas in their head. It takes a lot of training for most Aikidoka (and other martial artists) to get past the intrinsic assumption that their style is the best. So this has led to Aikidoka showing up at a dojo with a "chip on their shoulder".
The difficulty for the new instructor lays in their own sense of insecurity and desire to be "perfect" in front of their students. When challenged in the least by such boors, the new instructor either strikes a posture of perfection (usually a mistake) or they cave in and devalue their own training.
From my perspective, the best Aikido instructors teach their students. By this I mean that those who are actually teaching, teach. Those who want to show off are busy showing off. Those who rely solely on their rank, rely on their rank. Only those who teach others and look to better their understanding are worth the time and energy to train with. The others are like dessert -- fun to watch, but ultimately entertainment. Thus the "boors" who show up are entertainment of a sick and horribly fascinating type, but not anyone you would want to sit down at a meal with.