With regards to screen burn I've noticed a couple of things. Color CRTs don't seem to burn as "deeply" a mono CRTs. I've seen several mono CRTs that were used for either surveilance monitors or text displays where the burnt image is clearly readable when powered off. When powered on with a full white (or green, etc) raster the burnt areas weren't just dull, they were totally dark. This also happens with the old orange plasma displays used in some computers.
A while back here a load of ex-TAB 21" Orion TVs hit the market. The were used to display race information on teletext pages. When powered off several lines of text were clearly readable and several others visible as indistinct "shadows". When powered on it was only just noticable on a full white raster. Viewing a normal program you couldn't really see them unless you practically had your nose up against the screen looking for them. I sold several and never had any complaints or comebacks. As long as the customers got to see them running they were happy to take them, even after I explained the screen burn to them as showed them what they looked like when switched off. Of course it helped that I was selling them for half the price of a non-burnt set of the same size, and this was before the used TV market crashed. No-one would even ask about them when they were switched off, even when we dropped the price off the last couple of $20 to clear them out (this was back when a used 21" set would easily sell for $100, even without a remote).
I have a couple of Sony Trinitron studio monitors that were pulled from an edit suite. Both have time codes burnt into the bottom of the screen, but I don't really notice it. Otherwise they have beautiful bright sharp pictures with better color and geometry than many of the 1 year old sets that come through here. I like them enough to use them daily, one as a bedroom set and one in the workshop. Lately I've been watching more movies in the workshop than anywhere else (gotta test the DVD players before they go back out
).