Oops, you are right. I didn't get it in the first place, so I wrote down this table:
The table lists all possible sticker combinations. If the 3-letter-combination is followed by another letter, then this letter denotes the dwarf that says the right answer. What I didn't see was the fact that every combination that is not answered by A or B ends with "black", so if A and B remain silent, C knows that his hat is black. Stupid me.Code:BBB
WBB
BBW B
BWB
BWW A
WBW B
WWB
Greets,
Philip