Inbound links are good. Google says so. They bring link power (aka link juice).
If a site links to an old or non-existing page then you don't get the juice. That's a waste.
Follow such dead links and you get a 404 (not found) error.
Google Webmaster lists all the 404s it has received from your site. See:
Diagnostics < Crawl errors < Not found
See how Google cares about you?
To get the juice from these link you need to implement a 301 (permanent redirect) to another page. Choose an appropriate page.