On a multi-user system (such as a MUCK) that lists everyone connected, sorted by the duration of their current session, the botspot is the last entry in the list, or the person who has been online the longest.
Since bots by definition can remain connected for days on end without human intervention, they typically occupy the last entry in such a user list; this is where the name "botspot" comes from.
Consequently, the botspot can be a challenge to achieve on systems that have an idle-out or automatic disconnect. Folks in the botspot position are sometimes ribbed for "having no life"; in the old days of the Internet they were also often admired for having such reliable network connectivity.