It would be interesting if an aerosol spray could make visible all the electromagnetic fields present in our house, or environment...and disconcerting for some too.
Yes, this would be an amazing aerosol spray can!!! Anyone ever try to shoot your layout with a video camera in the "Infra-red" mode? I wondering if anything shows up? I know my TV Remotes did! But my camera is broken now 
The only controller I think might show up on your camera is the mini remote that used to (maybe still does?) come with some MTH starter sets. That was optical (infra-red) like the entertainment remotes. Pretty much everything else discussed here is RF, which if you could see with a camera would make the camera mostly unusable (at least for taking nice pictures) in today's world! 
Lots of good review in this thread, btw, thanks to all. This is one for the local archive.
-Dave
For any working layout, you must have an effective continuous outer rail, even if it may have insulated gaps on one side or the other in places. Otherwise your trains will not work under any system. For besides the TMCC/Legacy signal, one half of the AC power is supplied by that rail. 
