Reclaim Old Posts?

Supposing you have some old posts on your forum that are no longer relevant. For example, maybe it is a post about a sale of a domain that no longer even exists. Are there any advantages to reclaiming the post and adding other content rather than deleting it?

 

I run into this all the time with the system I have setup. (buying old forums and merging them)
I check to see if the old thread or post is getting traffic, if it does, I'll bump it and add more content/relevant info to the first post.