Well in recent years there's been faulty power supplies (premature failing), Purple snakes, Faulty panels (vertical green line) rising Blacks & now floating blacks.....quite enough to be going on with I think
Floating blacks have been around since at least the PV500. It was one of the things that put me off buying it before I finally dipped my toe in with the PX600
I haven't really noticed them on the PX600, but certainly seen plenty of snakes in my time. Although greatly reduced since it went in for the "fix"