Can vintage dials be cleaned/polished?

Always risk, and I have seen both positive and disastrous results- the last I took a gamble on was a silver dialed Seamaster where the lacquer was already compromised by moisture damage and it came off with the lettering- that watch ended up getting redialed and sold.
But, with a light touch and an experienced hand, miracles can be achieved.
I’ve shown this one several times here and is a great example of how removing surface grime is sometimes all it takes.
This OPD had a fine layer of haze across the dial and indices making it look flat, dull and lifeless- it was on the surface and was easily removed using the sticks @Archer talked about and a slightly damp q-tip on the brightwork. The second hand was a goner (replaced with a NOS hand) but the minute and hour hands cleaned up beautifully without any loss of lume...the man who did this has the hands of a surgeon and patience of a saint.

Those are indeed variable and yes, crystal was a mess and he polished that out (and tried to smooth out the chip on the edge)- I should have had him take a pic when he took it apart. It didn’t look “bad”, just kind of hazy and dull, and the hands had surface grime. He got most off the hands (some was very light damage to the finish and he left that alone), but overall the difference although subtle, makes the watch look 10x better.

My only point here is that yes, sometimes things can be slightly improved- but not always and not without risk

Here is another example of a light touch. I got this from a fellow member. Hard to see in the before pic but the dial has light surface speckling from moisture and little flecks of crud about the dial. It also had a light ring on the dial where it looked like the hour hand had contacted the surface At some point (barely visible on the pic but it’s there.

It wasn’t enough to really bother me as it was in great shape- but my guy took it to the next level...with a very simple light surface cleaning.