Bad Name Reuse is the practice or act of using a name (such as a URI in RDF) in a way which is incompatible or inconsistent with prior use.
We often imagine the first several uses of a name being made by some self-consistent entity, the "namer", who is likely to use the name "properly" for at least a little while. After that... when time goes by and others start to use the name in different ways... that's when bad reuse can start to occur.
It can be done by accident (a misunderstanding, a typo), with benign purpose (trying to move the meaning in a better direction), or with malice (trying to redefine the terms of a contract).
It is different from NamespaceSquatting, but they are intertwined.
It is even slightly different from NamespaceDistortion, which is based on the idea of incompatibility with the namespace document, instead of with all prior documents.