Things really are that bad.
For added fun, the manufacturer of a 720p HDTV I used to have had apparently decided that this whole EDID thing was too complicated, so had copied the EDID verbatim from a Thinkpad monitor (the X server log actually printed the display's identity as "Thinkpad"). The Thinkpad monitor in question was apparently a 5:4, 1280x1024 model. So I got the middle 90% of my desktop, stretched horizontally by 40%.
The TV I currently have is detected by my graphics driver as 1360x768, for some reason. I don't understand why the vertical resolution is mysteriously correct. Thankfully it can be told not to scale/overscan at all, so I just have a 6-pixel black bar down one edge of the screen, which I can cope with.