Residue...
Other causes could be:
- slow rotation of the spray arms. One of the old UK Hoover Service Data Books mentioned problems with upper basket in a model of 'Crystaljet' dishwasher (misaligned basket, spray arm bearings worn, filter not seated correctly, etc).
- I recently found that 'Finish Powder' left a fine white coating right through the machine and the load, as if someone had been flinging talcum powder around (they hadn't!). Salt and rinse-aid were used. Tablets don't leave the residue, which makes me think that the powder has been deliberately neutered - either by Reckitt-Benckiser themselves, or by policies set by the meddling EU. Which? were also underwhelmed by the performance of the Finish powder.