Sgt_Kickaxe - 10:46 pm on Jul 27, 2010 (gmt 0)
like a fine wine or do backlinks age more like bread, getting moldy and finally becoming so decrepit and stale that they are no good at all.
They likely do both, depending on their surroundings. If the page linking to yours is on a site/page that has improved I'd imagine your page will benefit and will pass that benefit along. If the link is from some old, never used, forum profile it likely rotted any value away long ago.