Great idea! It think it will pay off to be more aware of text during the day and it really makes for a great RC (works quite reliably most of the time). I remember some months ago I was doing this as an RC and it happened during a dream where I saw the brand under a TV set and tried to read it. It was very funny because I didn't think it was a dream at all, I was clowning around announcing that I'm reading this and if it changes it's a dream. I was completely shocked when it did change.

About text being present, I wonder if we are just not paying enough attention to it. Maybe it is there, like our mind would generate a familiar set of objects. It might be a good idea to list and think about all the places text is present - books, street names, brand names (these tend to be more constant in my dreams btw?), PC, tablets, mobiles, magazines, all sorts of ads around us and on most products we buy.