What is the orientation of these caps?

[GibsonGM]

There is much potential for confusion.

Same as with an A-meter...

It seems odd to connect in series something with "reverse" polarity as all series elements in a circuit are connected with a (+) to (-) order...

Exactly.  I've never come across this, but you never know (crossing fingers).   It looks like if you're designing/building your own thing, you wouldn't have this issue (what Paul said, re. rectifier - that's how I'd view it too, just innately or something).   I'll keep that in mind, tho, during repairs!

The closest I've come to this is fixing a dead 2-channel  CRO.....someone blew a diode by likely over-voltaging the input.  Got it for a song, and had the working channel to compare with the not-working one...I do recall some confusion about diode orientation, as the working side seemed to give a "non intuitive" reading...I just mirrored it and it was fine.  So maybe that WAS the same kind of thing! 

Neat info, not something I'd ever given much thought to!