for or against? personally i have no problem with exterminating a spider, but some people are heavily against such a thing and demand that it's 'set free' back outside.
imagine what it's like though, for a spider to be sat there on the wall, just chilling, then BANG. out of nowhere it's dead.
the scary thing is some of them survive the first hit. if we were hit by something with the same force, on the same scale, we humans would be mincemeat.