I have a phobia about losing spacers and putting them in wrong.
Witness marks - with paint or a Sharpie - are ALWAYS a good idea!
You can save the swear words for other projects.......
(Did you know that the ink in a Sharpie is alcohol-based? Alcohol takes
it off completely. I use Sharpies on stuff all the time. Buy black for
light-colored stuff and silver for dark stuff. Use it in the kitchen, too.
Write right on the container before it goes in the 'frig or the freezer
with the date and contents. Wipes off with rubbing alcohol so you can
use the container again with something different in it. Tell your wife - you'll
look like a HERO!