Cooties, as everyone who has spent time on a playground knows, are an insuperable stigma.

Although dictionaries may attempt to define cooties as some form of small insect, the true meaning has long since passed out of the realm of the literal and into the abstract, even the metaphysical.  When anyone of social standing says you have the cooties, you simply have them.

Because the claim doesn't have anything to do with bugs, you can't dispute it by offering your body for detailed inspection.  It is also futile to resist the classification with verbal protests.  To do so would be like saying, "I am not a geek" (or dweeb, or wonk, or whatever).  Such a protestation not only makes you immediately laughable, but as a result also tends to prove the original derogatory claim.

The principle of cooties, at least in its broader metaphysical sense, persists in our behavior well past childhood, following us all the way to old age and the grave.  The only thing that changes is the way the principle is nuanced.

For example, Tom Wolfe describes in his retrospective of modern architecture From Bauhaus to Our House:  Why Architects Can't Get Out of the Box how, at a certain point in European social evolution, virtually any creative effort could be ridiculed into oblivion by the comment, "How bourgeois."  Also during this period, a circle of influential architects developed who limited their designs to box-like shapes, and who disparaged any form that was more expressive or distinctive as being "bourgeois."  Wolfe credits this particular term of approbation with cowing most of a generation of architects into effectively avoiding any shape that was not a box.

In this context, being "bourgeois" was a synonym for having the cooties.