I download swatches from all the manufacturers that provide them. When I'm making a quilt in EQ, I try to use the exact fabric, but that's not always possible and I use a swatch that is the same overall color and value.
Scale is usually problematic only for focal prints, where I'm trying to put in fussy cuts, but it can also affect how the swatch looks in overall color and value, so if the scale is off, I just substitute a swatch that matches those the best.