When I was at the SMM3G in '04, the distance targets were (I think) 10" flashers with a black plastic sheet as a backer. Worked pretty well (until the backer got loose and blew in front of the target).
The worst I experienced was at a local rifle match a few years ago. The area in front of the steel target was loose dirt, and if you shot low, or left or right, a huge cloud of dust would be kicked up and you couldn't see the target at all.