Well, trying to figure this out, the dust is
responsible for the brightness of the sky in the 5-50 micron infra-red band. Increasing the amount of dust will start to reduce the +24 bonus for a target silhouetted against deep space (
Spaceships, p44-45). However, I don't know how to work out
how much dust you need to reduce the bonus.
The mass of the solar system's dust cloud is small on a solar system scale (about a 15-killometre asteroid), but quite large on a human industry scale. You also have to grind it remarkably fine, and disperse it very widely, which sounds expensive. I think you'll need to be really quite high-tech to do enough of this to be noticed, never mind to have any side-effects other than annoying astronomers.