Soaps/Creams the leave the least scum/residue in the sink

[DarkSpy]

I wanted to know which soap/cream you use, are the easiest to dissolve in water and don't leave or leave the least scum residue behind.

I've now added this metric when evaluating software, and is as important as slickness and protection.

 

[ehv]

How do you measure this? On some sites people post that tallow soaps increase clogging. I think this is based on the idea that fat cloggs the drain. This is true, but is the percentage tallow really enough? I don't know.

 

[DarkSpy]

The easiest way is if the soap, when you rinse your razor, etc, is easily soluble in the water or if it keeps it's foam form.
Another part is if it stains and leaves a white residue in the chromes of your sink.
I can't say if this two are connected (I would say so) or are independent occurrences.

For example, Proraso Single Blade cream clearly has problems dissolving it's foam.
But I'm not interested in the worst I'm interested in the "cleanest".

 

[Kingjack]

Glycerine soaps.