Usually I suspect there's always a Lurker, if I cannot see 5 players pushing down a side. But there's only 1 time, I'm ignoring this and it's during Pistol rounds.
It's not happening very often, but I usually got for a free ultimate orb during defence on pistol rounds, when I hear that players are rushing down another site. But there's tines where I die from a random lurkers which gone and done a slow lurk on Pistol rounds.
But I feel its just something that other players never do in higher elos, and it's just a complete coincidence.