Realize that visual appearance alone is not a good indicator of soil quality. A material may look like a quality topsoil while it is unacceptable due to high salinity, pH, or other factors. Take a sample of soil and attempt to crush a few dry aggregates. Ideally, dry aggregates crumble under pressure. Be suspicious of material that is extremely hard.
Hard soils indicate low organic matter or high clay content.
Remember that this soil will behave similarly in the landscape. Wet a few aggregates and break them down to individual sand, silt and clay particles. Ideally, there should be a combination of some gritty, smooth, and sticky particles. Recall that this material will behave in a similar way when wet in the landscape. Check topsoil color.