Along the same lines as the various logo'ed tags over on SF, and the colored tags on the Meta SE sites, it would be nice to see some kind of style applied to the spoiler tag here on G.SE. It could be as simple as a soft/dark red, or black background (with appropriate text color too, of course), or a small icon that properly indicates the meaning of "abandon all hope at being able to complete the game on your own, ye who enter here" to all digital passersby.
Skull and Crossbones icon, maybe? In addition to a black background? :)