  Users on Twitter are commonly identified by their profile names. These names
are used when directly addressing users on Twitter, are part of their profile
page URLs, and can become a trademark for popular accounts, with people
referring to celebrities by their real name and their profile name,
interchangeably. Twitter, however, has chosen to not permanently link profile
names to their corresponding user accounts. In fact, Twitter allows users to
change their profile name, and afterwards makes the old profile names available
for other users to take. In this paper, we provide a large-scale study of the
phenomenon of profile name reuse on Twitter. We show that this phenomenon is
not uncommon, investigate the dynamics of profile name reuse, and characterize
the accounts that are involved in it. We find that many of these accounts adopt
abandoned profile names for questionable purposes, such as spreading malicious
content, and using the profile name's popularity for search engine
optimization. Finally, we show that this problem is not unique to Twitter (as
other popular online social networks also release profile names) and argue that
the risks involved with profile-name reuse outnumber the advantages provided by
this feature.
