I guess it would depend on whose definition of trash you're basing your judgement. For instance, my husband is a Whovian, but Dr Who is really escapist TV, some of it very, very k-rap TV (although some is brilliant). He sort of agrees with my assessment, but some of his friends would try to lynch me if they knew that I held that belief.
Lots of documentaries are really k-rap TV. Have you ever watched a documentary on something you happen to know a lot about? It really puts the ones on things you don't know a lot about in perspective. They are good to watch, and you might be getting correct information, but you should take it with a grain of salt. Then there's the sort of freak-show masquerading as a documentary or the reality programmes that are meant to be serious and worthwhile (ones on obese people losing weight as opposed to ones on people stuck in a house and voting each other out). But if you say "I watched an interesting documentary last night..." most people will think that you're likely to be more cerebral than someone who spent the night watching something like "Little people, big world" or whatever it's called. I can't see how watching bad TV is any worse or better than reading bad books. Exercising your imagination is great, but some books are so bad that it doesn't happen. Plus, it's not like you're totally flatlining whilst watching even the worst of programmes, or at least I don't shut down my brain.
However, I agree that getting people reading is important, especially kids. When I was young, I read everything and anything I got my hands on. I credit the identity of being a "reader" for my love of books that endures to this day. And, for the most part, I had unfettered access to any book in the library or in the libraries of the adults around me. I did have to sometimes sneak things, but not from everyone. Because I wanted to be like the other readers who appeared smarter, I read and became a reader. It didn't matter what they or I read.
When it comes to propaganda, I think it is important that an adult helps a child recognise it for what it is. If these skills are taught when someone is young enough, you don't really need to worry no matter what they read.
All this said, I think that encouraging kids (and adults) to read good books as well as trash (and to consume higher culture as well as low) is important. Of course, some of this will be subjective, but even striving for it is a good thing. Wasn't it someone from this forum who said that their mother made a "forbidden" shelf of books she wanted her daughter to read, thereby ensuring that she read them? I think that's a brilliant idea. But more than anything, I think someone has to become a reader.
As far as what I read now, I could care less if someone looks down on it. I will likely try almost anything, but I give up on a book pretty easily. I don't think life's too short to read trash. I think life's too short to read stuff you don't like unless there is a larger goal. I do force myself to get at least one classic out every time I visit the library, and that system sort of works for me. But I'd much rather see someone reading than not even if it's just something like bodice-rippers.
ETA: I guess I can't see how watching something like "Eastenders" would be seen as a worse use of time than reading something like the Twilight series if I had no interest in the latter but enjoyed the former. Or that I should feel guilty about watching that rather than reading something lofty (which I do at other times) or to force myself into reading something I have no interest in reading, even though it's a classic (like, say, War and Peace) instead of keeping up on what's going on in Walford. I might have finished W&P in the time I've devoted to "Eastenders" in the past year, but would that have made my life all that more enriched if I hated every moment of it? Sure, if I never got any high culture, then I could see curbing my trash intake, but FFS, trash is nice as well.
BTW, when I say I think something is horrible (like The Lovely Bones), it doesn't mean I look down on people who enjoy it. I know I can't really expect people to behave the same towards me and my love of very low culture things, but I have more respect for people who do manage that distinction.