I did contact Apple itself, and they found another authorized service provider nearby. As it turned out, the stuff was, in fact, some kind of liquid, but neither the service people nor I can figure out what the hell it was; not only didn't water or saliva move it, it was also not soluble in alcohol. However, Apple authorized the repair to be done at no more than $329, and in the end it only cost me $309, which was a much saner cost all around.
I do have to go back to the store and apologize, however. Next time I head over to Crossgates.