So the graffiti problem was under control by the early/mid 80's?
Absolutely NOT! Remember what I said, the R62s were the FIRST graffiti-free cars in 1983-in other words, the graffiti-free era was just beginning. I would say that the TA didn't really get a strong hold on graffiti until 1987 and even then there was more work to be done.
Did the cars that had graffiti simply not get any worse until the GOH got underway?
It depends on the car. For example, some cars were just repainted and kept free of graffiti a couple of years before overhaul. Those cars were: R32s, R33MLs R40 slants (a/c units only), R40Ms, R42s, and R44s & R46s (these two were just cleaned up-never painted except for beltline).
Others went from graffiti straight to overhaul. For example: R10s (only 110) R26s, R28s, R29, R30s (8250-8350), R30As (8350-8411), R33WFs, R36MLs, R36WFs R38s, R40s (non-a/c).
And others were just painted and kept free of graffiti, then scrapped. Those were R27s (only about 20-then scrapped in a matter of weeks), R30s (8412-8569) and a handful of R17s as well as about 1 or 2 R22s.