For my clients I tend to check on a monthly basis, who we link to, and what links those websites in turn link to. It’s not enough to make sure that the websites are live, rather one would need to check visually what is being display on these websites and where the links go to. Also it is important to monitor if sites are being dropped (i.e. failed to be renewed, and subsequently registered by someone else) or if they have recently changed hands. Being anyway associated with dubious domains has the potential to damage your SERPs (the so called “bad neighbourhood” effect). Often when these sites are bought or picked from the dropped list, the old version of the website will remain (or re-appear, scraped from somewhere like google cache or archive.org) and then over a period of time these dubious links will creep in. This all sounds like a bit of work, but in the end it can avoid damage to your online reputuation. It’s not enough just to have a google alert, which emails you whenever someone mentions your website/brand, online reputation management should start at home, on your website. Have a look at your older out going links to make sure that they still work and they still link to the website you intended to.
Just today there was a high profile case of the British Home Office linking to a Japanese porn site on BBC News.
