True screen burn can also be seen with the TV switched off.
I've never heard of this, and do have
burn in (unless three year IR is an actual thing) on my Panasonic. You can't tell anything is wrong with the set off.
Wish I had known when I bought mine how much babysitting
some plasmas might require so I could have done things differently. Some of the newer sets have better screen washing options too than others. Mine just has a generic white scrolling bar that kind of helps, but watching full screen content helps more.
My plasma at least just isn't good for unbroken, marathon playing of anything with static images such as a large HUD. I ended up with UMvC3 health bars stuck on the top of my screen for over five months from a single four hour session in training mode. They finally went away, but I've had SF4 super/ultra meters stuck at the bottom of my screen since forever. You can't really notice them unless you are about two feet or less away from the screen and it's trying to display black, or just a really dark scene or when something like the PS3 is first hitting the dashboard, where it's extremely apparent due to how the pixles of the meters seem to lag behind the rest of the screen when first warming up. Now I just play fighting games, or HUD heavy games on my monitor. My monitor is better for fighting games anyway though at 12ms, while my plasma is at 20ms.
I don't regret buying this set though. For the price I paid, there's still not an LCD anywhere close that can match it for picture quality, and out of the box with THX mode it has some of the best non-professionally calibrated colors. It should last me another five years at least, where hopefully 46'' - 50''
flat OLED panels are actually being produced, are reasonably priced, last longer than a few years and also have low input lag. Don't really care about 4k either right now. OLED by default still looks more natural. The 4k OLED are about ten years away at least for affordability. Most midrange gaming PCs and none of the consoles will be doing 60fps higher than 1440p before then anyway.
*1440 on Ultra or whatever settings, before someone chimes in with how "most midrange" PCs can already do this.