I do have a can some where but never used the stuff, does it work?

No not really as the heat burns it off first...!!! Much better to use an old file and knock the spatter off yourself as it then lets check to see if you have missed any welds.

i find it helps on stuff thats say, next to the item thats being welded for eg when your adding something to the chassis and its getting splattered, just a quick misting normally helps

yes thats how it's intended to work, reducing the chances of splatter sticking to fresh ground steel or shiney new ERW.