Yes, that meter has seen better days. No, that was water and rust. My guess is that after it was retired due to a hot terminal failure (B phase line terminal burnt badly enough to char 3" of insulation on the current coil and cause the terminal block to crack into 4 pieces), it was parked "out back" behind the golf course shop until it was finally gathered by the municipal light department to put in the auction. It was still attached to its service cabinet when it was in the auction.
I'm already almost finished with a rudimentary cleanup of the Westinghouse meter to make it a fairly decent static display unit. I'm sure you are familiar with what a PITA it is to reassemble a polyphase A-base terminal block into the housing... now try it with the block in 4 pieces. :-P
Incidentally, that was one of only 5 electromechanical meters in a tub of 50 meters - ALL the rest were failed 'smart' meters! In the end, there was only one I deemed a permanent addition to my collection - a GE I-50-S (Form 19S - convertible 60-amp model for use in place of a Form 1S or 2S meter), and which obviously was used indoors, as it only needed a bit of cleaning to make it practically NOS condition.
I can imagine what frustration that must have been in trying to explain solid-state meters to someone that only knows the old electromechanical models.
What register was that you speak of? the JEM?
I did work in the industry for a while, doing on-site testing, mainly single-phase meters, for a number of coops and municipal utilities, but I tired of the travel (and a few incidents made it inadvisable for me to continue in that particular job) and moved on to other work.