In my book, there is absolutely no difference between lurking and keeping quiet. If a player isn't posting, that means one of two things: either they've forgotten about the game (non-participating), or they are following the game, but not posting (lurking).
Non-participants must be "prodded" by the mod. If their silence continues, then they can only be dealt with in two ways: replacement or mod-kill.
Lurkers are much trickier beasts. Everyone, at some point, will lurk in a game. Sometimes, you have a really ridiculous role, and you don't want to have to face an early bandwagon. Sometimes, you don't have time to come up with content because your SO is feeling needy. Sometimes, the mod makes you a Mime. Most times, you're just scum looking for a free ride to the endgame.
Actually, lurking is not inherently scummy, but it's in the interests of the meta-game to treat it as such, because obviously a game with no one posting is a sucky, sucky game. But you have to have balance -- if all the players in the game are posting 12 times a day, all the meaningful content gets lost amid the waves and waves of non-essential fluff. Games tend to naturally balance out... if I'm in a game with MeMe, CS, mathcam, and there's a mith vs. Antrax point-by-point analysis fight going on, chances are that I'm not going to be posting up a storm. But, if the game's going slow and I have some good ideas, I'll step up and try to get things done.
My mighty 0.40 post per day count shows that I am not the kind of player who posts every time I'm Scumming. However, I do try to be active and valuble to whatever game I happen to be in. If I find myself lurking, it's because I don't have anything to add, which is usually a sign that I'm not giving the game enough thought. This is why I limit the amount of games that I'm in.
