Discussion: Do you cast your characters while you're reading? How do you imagine them?

Hey guys :)

I want to apologize again for being less active lately, both on the blog and on twitter. There's a lot of change going on in my life right now and I'm trying to deal and find a balance. Mostly I'm just losing myself in one book after the other, which leads to reviews piling up, which leads to me sticking my head in the proverbial sand... yeah.

Anyhow, this is a discussion post! I'd like to talk about how we imagine characters in the books we're reading. I've noticed that a lot of bloggers (and also authors) 'cast' the people in the books they read or write, i.e. choose pictures of actors or models they think represent or resemble the character.

I can never resist an opportunity to show off this cover

Apart from the fact that I'd be way too lazy to search through all those pictures of hot dudes and ladies (because let's face it, they usually are good-looking) I admit I personally don't really see the point. When I imagine a character, they never resemble any other person I've ever seen before, be it from my own life or from a movie/advert/whatever. They just pop into my head as I read them. Even if there is no clear description from the get-go, I always have an image in my head that  I can then adapt/concreticize. Before seeing all those casting posts, the idea of looking for that type of pictures never crossed my mind. But I've seen in a lot in guest posts or on authors' Pinterest boards.

The only thing I admit to is that I sometimes 'lift' a character off the cover if I like it a lot. For Nevermore trilogy is someone I imagine pretty much exactly like the guy on the book cover. Same with Daemon from Obsidian, because that guy is so in-your-face everywhere before you even start reading the book that it's impossible to picture him any other way :P
instance, Varen in Kelly Creagh's

So I'm interested... am I the only one who isn't into casting characters? Those of you who do it... why? Or why not? Or how? I'm curious :)
Also more generally, how does the 'imagining characters process' work in your brains? Do you base them on other people? Do you even 'see' the book in your head like a movie at all when you're reading? The reading process is something I find absolutely fascinating and I'd love to hear how you experience it!