This is a normal function of blood and, furthermore, its extent cannot be easily quantified with live-blood work. The extent of this clumping, this rouleaux formation can however be easily measured in standard blood work as sedimentation rate, or SED rate. SED rate is a general indicator of inflammation. We generally expect the SED rate to be elevated in inflammatory conditions such as arthritis. But SED rate is a very general and imprecise measure, and medicine pays little attention to it nowdays.
Some microscopists claim that live-blood can be used to diagnose for parasites.
In live-blood analysis we take a small drop of blood, perhaps a billionth part. I've looked at hundreds of bloods and perhaps I've seen a parasite once. We do, however, see a lot of break down products from the blood cells. In particular the cell walls of the red cells will often unravel just like a knitted jersey. Wiggly moving threads unravel from the red cell walls.