Genuinely curious. Would you be more likely to watch a film or tv series because an actor was left wing ? Would you not watch something because an actor is right wing ?
I genuinely only know about 10% of the names mentioned so far, I don't pay attention to actors names - knowing who an actor is spoils it for me. The magic of the silver screen is being able to suspend your sense of disbelief so the less i know the better, as a rule of thumb anyway. I find the modern day celebrity of actors pretty bizarre.
But in answer to your question, no, i wouldn't NOT watch something, though there are plenty of actors, whether i know who they are or not, who i take a dislike to for whatever reason and they can spoil a film for me by being in it. Id expect there's suspicious personal politics lurking there somewhere in those judgements!
Obviously with something like a Ken Loach film you watch it knowing what it is, but that's not a situation that comes up very often. Id expect left wing actors to take on more interesting roles though, so that might be a draw.
I really like films with unknown or unprofessional actors, especially when children. Two that spring to mind are Michael Winterbottom's In This World and the Russian film The Return.
And then theres the politics of the producers. State financed films, especially of the soviet era, Russian or not, have a certain something to them. Usually with a US studio film its more a case of marveling at what they've churned out this time. The most recent trilogy of Star Wars films should be taught in economics classes.
Rambling answer <Ive got time on my hands
ETA: cant watch John Wayne films, and I like a Western. Suspicious about Clint Eastwood films too (apart from the Italian ones he was in). So actually yeah, there are films I wouldn't watch. Probably some other names like that if I have a think. Antiques Roadshow is painful