Had some discussion about the need to wipe the basket in the portafilter, or flushing with hot water. All respectable barista knew that you need to wipe clean and dry the basket before dosing.

Different practices:
1. Wiping only. Totally sufficient. No flushing with hot water is necessary.
2. Wiping and occasionally flushing with hot water when deemed necessary.

Beginning. Starts with everything clean and dry.

Before the 1st shot

Pulling a ristretto

After 1st shot

This is after 2nd shots

Different view after 2nd shot

Stains… or to some, coffee oil coating the portafilter and basket.

After wiping, the basket it clean and dry.

How the underside of the basket looks like. Some barista like to have the basket coated with coffee oil.

After flushing with hot water.

How the spout looks like after flushing with hot water.

I guess it depends whether one consider those left over as undesirable stains or taste enhancing coffee oil.