Can't help getting dirty. . .
I like the example. It works well since what makes this man horrible is entirely unrelated to his business. There is nothing wrong with buying furniture, so normally there would be nothing wrong with buying from this guy (unlike, say, patronizing a hit-man). The trouble is that if you buy his furniture, you are making his life a little easier, some of your money goes into his pocket, and, in some small way, you are affiliating yourself with him.
I can understand (and share) your revulsion at dealing with this guy, but I wonder if this position is realistic. Any society, any time you live with others, it seems quite likely that you cannot help dealing with people who are guilty of serious wrongdoing, from co-workers to family members to janitors or CEO’s at corporations that supply things you need.
Do you think it is possible to avoid cooperating with evil, are there some evils you’d think you can cooperate with, or have I misunderstood your position?