I know that some reddits (for example /r/gaming) do this using links. You write [something goes here](/spoiler) to get something goes here. It should be fairly easy to adapt to LW, since LW is based on reddit. In fact, it is just a matter of changing the stylesheet:
a[href$="/spoiler"] {
background: #888 !important;
color: #888 !important;
}
a[href$="/spoiler"]:hover {
background: #bbb !important;
color: black !important;
}
As an alternative that you can use right now, put the spoiler in the tooltip of a link: [spoiler](/"something goes here"), i.e. spoiler.
Basic reddit code -- unlike the /r/gaming 'hack' -- supports the following syntax: [text goes here](http://linkgoes.here "hovertext goes here") which gets you: text goes here . :-)
To judge quotes on their own merits, if without some context, I propose an experimental thread in which the original authors of quotes are somehow hidden.