keep speedy lock on?

Locks are on the epi 25's, but not on the mono 25, cerises, and khaki graffiti. I don't want the vachetta stained, or the print rubbed (esp the graffiti). Yes, I am anal about my bags!
 
i took my lock off after reading a post saying that it will leave a black mark on the tab - i had the lock on for about a year (maybe) less and it is a small black mark... so no more lock for me!
 
I keep the lock on the bag when in use and take it off to store my Speedy. I keep the keys attached to the D-ring on the inside of the Speedy!

What did you girls mean by putting tooth paste on your lock? Does it make the lock shinier? If so, which brand/type is best? thanks! :P