[mook]

That makes "do not dry clean" difficult, since it'll effectively be a double negative.

(I do think the circle is difficult, but that's probably because I don't typically wear clothes that one would think about dry cleaning)

[bombcar]

Then you'd just have a drop, but true, there are three states - dry clean ok, dry clean bad, dry clean mandatory (where the first is do either, but that could be indicated with no symbol at all).