So you want the brushes to smear more than blur? ASP is really good at this.
With the smudge tool selected in the toolbar pick a smudge brush (or even the pigment brushes are good for this) and toggle Pattern, Aux Stamp, Jitter, and Dynamics off.
In the wetness section, set Blend transparency to 'Full', turn off blend radius (to disabled)
set Mix Rate to around 15
Set wetness to at least 50% or more
Turn on 1px spacing smudge
Turn off dynamics, and make sure flow is 100% since these can really affect everything else.
Make ake sure your brush stamp is a simple shape to start. There are other settings that affect blur/blend but start there.
Test that out on some flat color swatches (no space between them) to see what it's like. it should just pull color away from the swatches without blending them (but will blend with the transparency). Then incrementally turn blend radius up to a value you like -> he larger the radius, the more color averaging/blur will occur.
let me know how that works.
