Very high volume spray, would fog up an area nicely I would think, especially if one did something like ducked down an alley and left a cloud of OC behind, just don't have a tailwind you can't out run.
I discourage people from buying bear spray unless they actually have a potential bear issue due to the appearance of using the stuff on people (OC is OC for the mjost part, but sometimes appearances matter) but if you do have a need for bear spray I'd certainly use it on a bad guy if I had to.