I see these like most other comment functions and view each one based upon the value it has to my site visitors.
Whether is it a trackback (HTTP) or a pingback (XML-RPC) isn't as important for me as how it will help my site visitor.
If the link takes my site visitor to a truly valuable page, I approve it. If the link takes my site visitor to a spam page, I reject it.
I think my approval percentage is less than 0.01%.