Cartoon representing the quasar core, torus clouds, and a polar scattering region. Light rays towards the observer are represented and their polarization illustrated by arrows. Panel A: direct light from the quasar core (continuum source + BLR) reaches the observer and dilutes the light scattered off the polar regions. The quasar is in a type 1 state, and the polarization degree is low. Panel B: direct light is blocked by a cloud intercepting the line of sight. The quasar is in a type 2 / obscured type 1 state, and the scattered light is no longer diluted. The polarization degree is high during the event. Panel C: quasar engine is switched off. Only the echo of a past bright state is observed in the scattered light. The polarization degree is high and slowly decreases with time. The quasar is in a true type 2 state.