Expired domain abuse
Expired domain abuse is where an expired domain name is purchased and repurposed primarily to manipulate Search rankings by hosting content that provides little to no value to users. For example, someone might purchase a domain previously used by a medical site and repurpose that to host low quality casino-related content, hoping to be successful in Search based on the domain's reputation from a previous ownership.
Expired domain abuse isn't something people accidentally do. It's a practice employed by people who hope to rank well in Search with low-value content by using the past reputation of a domain name. These domains are generally not intended for visitors to find them in any other way but through search engines. It's fine to use an old domain name for a new, original site that's designed to serve people first.