I've worn my Yarmulka for a week now and my experiment's original time frame is coming to an end (I haven't yet decided whether I will prolong it for the first week of classes which start tomorrow in order to have a bigger sample and exposure to more people). So far I have not heard one outright antisemitic comment. Yet, two people have commented in a rude manner that at least implicitely made a negative attitude towards jews obvious.
In the store right near my house, the shopkeeper rather incredously asked me: "Is that a Jew hat?" I responded affirmitavily and no real further conversation took place. In the second incident a baldheaded guy in the company of a dude in a German national football jersey uttered to his friend: "That's is a Jew!"
In both cases it was not so much what was so said, but the way in which the word Jew was pronounced, that made clear that these guys had a very negative opinion of Jews. Still, it seems clear that antisemitism is less openly pronounced as I thought it would be up front.
One important aspect should be mentioned though, one that a friend of mine made me aware of: Most people seem simply not to know that a yarmulka is part of the jewish religion. If this is true, and I definitely have come to the conclusion that it is, then of course the experiment has not so much led to the aforementioned conclusion, but rather has failed due to a lack of knowledge on the part of its - unknowning - subjects.