inactive account
For when all of an artist's posts are inaccessible due to the account being suspended, made inactive, or deleted. This is considered to be a subset of bad id.
For Twitter, this can be detected if a post link shows the message: "This Post is from a suspended account".
For Tumblr, this can be seen in the blog's URL, as it will have -deactivated appended to the end of the URL, followed by the date of deactivation.
See also
This tag implicates bad_id (learn more).