Some will say you can't run them upside down but that is just not true.
That depends on the shock. Some you can and some you cant. Ask the manufacturer if you have that question. Most of the mono tube designed shocks with reservoirs are OK to do that with. I think, its the emulsion shocks that are not OK to do that with. So are many of the none gas charged ones, like rancho and procomp.
Personally I'd rather damage the shock shaft rather than the body. Especially if you're running an expensive race shock from Fox, Bilstein, Sway-a-Way, etc. Those shafts can be replaced for less then the body. Plus a damaged shaft will still travel throughout the its full range of motion, depending on the damage. If the body is damaged, the shock will try to stop at that point.