It is a pretty vague way to put it, but Inigo does have a vague idea of what the other means. Kind of. He thinks.

"Then are there others among you whose approach or method is more.. sinister?" He figures it's the best word for it, considering the figure used it earlier. And Inigo does figure some of the Arcana have to be that way, considering how the some people talked about them as a group. This figure doesn't seem so bad though.