Let’s face it 404 pages are a pain, for webmasters and for users. I absolutely hate clicking on a link and getting a 404 error page. However, what’s really our concern here is what it does for your SEO. What should you do about those 404 pages? Should you just leave it alone or should you 301 redirect all of them? As usual moderation and common sense is the answer to this dilemma. Randfish recently gave his opinion on when to redirect the 404 pages an when to just leave them alone.
Basically what he said was to just leave all 404 pages alone unless the page:
In short unless you can see that you’re really losing on substantial link juice then let it be. From the user stand point though I have to agree with Yoshimi that 301s can actually be more confusing to searchers then 404s. 404s are irritating but it is even more irritating to click on a link and be baffled when you end up back on the site’s homepage. At least a 404 page makes you realise that there’s a problem somewhere along the way and that you’re not just being crazy clicking again and again and encountering the same frustrating problem of ending nowhere you want to be. Of course, as Randfish says if it’s obvious that the URL was misspelled then a 301 redirect to the desired URL won’t be confusing at all.
To make 404 pages less irritating and baffling what you can do is to customise your 404 page. Jeff Atwood’s post on Creating User Friendly 404 Pages is a useful guide on how to do this. Remember though that a customised 404 page will not affect your SEO but anything that will make things better for your users is always good for your end goal.