Layered navigation generates URL combinations faster than anyone can review them, and the default position of blocking all of them throws away real demand.
The line I draw is whether the filtered set has its own search demand and its own answer. A single attribute with genuine volume, a color or a size that people search for by name, can earn an indexable page with its own copy. Two attributes stacked almost never can, and three never do.
What makes this harder on Magento than elsewhere is that the same filtered set is reachable by several URLs depending on the order the filters were applied. The decision is not one page, it is a family of them pointing at one canonical.
The part I have never been happy with is the copy. An indexable filtered page with no unique text is a thin page with a good URL, and writing unique copy for every filter that earns one does not scale past a few dozen.
How are you handling the copy problem on the filtered pages you decided to index?
Swiss Knife SEO ModeratorAdministrator