The key is to remember that the used look should only apply to technology used by people who can't afford the latest thing or maintain older things to mint level.

So the Naboo Royal flight should look shiny and clean as it's hardly ever used and mostly ceremonial.

The Republic courier ship should look clean because it's a vehicle used by the political arm of a rich galactic government.

Arguably the only ships in Episodes 1 through to 2 that should look used should be seen on Tatooine and Slave One.

In ROTS the war has been going on for a long while so you can understand both sides looking a bit battered.

I would add damage to Coruscant in ROTS implying that the battle and the diversion of funds to the war has taken the sheen off the capital but it's still the Capital.

It should look shiny on the surface but get dirtier and grungier the lower down the huge city you get.

The Republic's official droids should look clean all the time so I would have a gold shiny Threepio (not made by Anakin) behind the Queen or Padme every time she might need a translator.

The pit droids and the battledroids in ROTS could look beaten up.

Largely this matches what was actually done in the PT.

The real problem with the worlds of the PT is that they are populated by boring characters and are the setting for nonsensical situations.

The missed opportunity of the PT was not seeing the X-Wings and Y-Wings when they were cutting edge and clean.

So arguably the films need more sheen on select items not less.