Non-town strategically lurking is fine, actual townies being super lurky and not really playing is what completely ruins it because you can't just lynch the scummy lurkers anymore. That being said, lurking until you get prodded (and especially past that) is bad regardless of alignment.
Cut by Bard being right. Part of the reason it's not so easy to do this is because of how many townies end up doing it now for whatever reason, and regardless of how bad it is, people don't want to play against their wincon and lynch someone just for not playing. The biggest issue is more people signing up who are going to lurk really hard regardless of alignment.
If you aren't going to post, don't sign up for a game. Seriously. (Lurking because it seems ideal for surviving as scum at present is different, especially since it's a tried-and-true way to survive on motk >>)
Other cuts:Not being lynched is good if you're town. Achieve this by not looking scummy, not by lurking so that you can look scummy but not get lynched because people won't lynch you for it. Townies lurking makes it harder for town to win because even if you don't end up a likely lynch, you're distracting people with how questionable it is, and you're giving scum someone to sit on as an easy vote.
NNR:Really, if something like that happens, I view it as more of a fault of the setup then the players. It's kind of like telling players that they're not allowed to do what they think is most ideal to achieve their wincon.