You don't have to leave the DVR status indicator on the screen in one long setting for a burn to eventually appear. If you would pause the screen every night for say 15-20 minutes, after a few months, that image could burn in on a set that is susceptible to burn-in, like a CRT RP or a plasma.
Same is true for channel logos and news tickers. You could certainly get burn in from watching too much ESPN as they use a lot of tickers and prominent logos. And it is very true if you watch 4:3 programming in its native aspect ratio, with black bars on the sides. If there are shows where you don't want to stretch or zoom them because you want to watch in OAR, then always use the graybar 4:3 mode.
To reduce the chance of screen burn in, you should:
A) Make sure your set is properly adjusted for brightness and contrast. If set too high, it will burn in much faster.
B) When you pause a DVR for more than a few minutes, set the TV to a "snow" channel, or a blank video input. This is especially important if you do this frequently.
If you buy a TV that is susceptible to burn-in, and then you don't take steps to avoid burn-in, then it is not Dish's or CNN's or ESPN's fault when you get burn-in.