Does radioactive sludge give spectres their invisibility?

[osjclatchford]

You can meet Spectres outside and far away from any nukage (like in Doom2 map3), so I would not say that radioactivity is responsible for their invisibilty.

This is why I was curious about the actual statistics. Personally, I put them in darker rooms or places with very gritty textures, because it's where they're most effective as an ambush attack. (Lots of crossover between gameplay and "canon" monster strategy here.)

indeed. this is their best kinda location...