"As I understand it, after a while it will stop indexing that content and forget it ever existed."
No they don't. I am still getting hit for content which was removed/moved 8 years ago. Baidu, Googlebot and a slew of others still visit regularly and generate a shed load of error reports in my stats. I have tried 301, 302, 404, even 401 to get them to sod off. In the end I tried putting blank content on some pages with noindex/nofollow and it still does no good.
It seems that once the content is there bots assume it'll always be there ad infinitum.
"As I understand it, after a while it will stop indexing that content and forget it ever existed."
No they don't. I am still getting hit for content which was removed/moved 8 years ago. Baidu, Googlebot and a slew of others still visit regularly and generate a shed load of error reports in my stats. I have tried 301, 302, 404, even 401 to get them to sod off. In the end I tried putting blank content on some pages with noindex/nofollow and it still does no good.
It seems that once the content is there bots assume it'll always be there ad infinitum.