After deleting events or groups the stream entries persists

Hi.

If you create an event for example, then a stream entry is created. After deleting this event the stream entry has also to be deleted because otherwise there is a error or a not exists page..

Same for groups or uploaded pictures or anything.

What do you think?
And also for seo its not very good if index follow is enabled and entries on google will be redirected to error or not exists pages..