I'm now coming to some pretty solid conclusions about penguin, just a few more days and I will have pieced together alot of information, but one of the things I have noticed, and so have a few others (Dori Friend) are dead links..

I have been looking over a few sites today and the sites that got hit badly have got way too many dead links pointing to them, so in this case it might not be a good idea to remove any links, changing them might help improve your anchor text diversity, certainly building more high quality links that will stick would be a good idea but so far there is mixed evidence, i.e; some people have said they have removed links and their rankings have improved, on the other hand I'm yet to see anyone speak out about diluting the anchor text and recovering but please correct me if I'm wrong..?? Perhaps this is because it will take alot longer to recover via link building and the people that have removed certain links have diluted their anchor text enough to escape the penalty.

A dead link is a link that has been removed, i.e you commented on a blog, Google crawled the link and the site owner removed it because it was spam, or you used a blog network, Google de-indexed the blogs and the owners shut them down and they are responding with a 404. Quality sources are more likely to remain active longer and less likely to remove your links.

This is why I believe if a site has been spamming hard, it may be very difficult to bring it back to life. After looking over my backlink profile for one of my sites, it's clear it could take me along time to recover it as it has got around 80% dead links, when it should be more like 20% and around 90% over optimized anchor text. In this case I will be letting the site go and starting again as I have got far too many backlinks, I would need to build 10k backlinks just to water down my main anchor. (EMD)

Still what is unknown is how Google are treating these pages, just to say one page that links to you with over-optimized anchor text is a spam page is unreliable as there could be many genuine webmasters linking out.

It could be if a certain amount of pages that are penalised (based on anchor text) have a link from a certain source and it has a high OBL then it could be considered with a good level of certainty that the page is being spammed however, I'm still seeing sites with spam ranking in Google, including comment spam and other spam, maybe they just got lucky?

It could simply be a site penalty based on anchor text, a few other signals and on page but not a link devaluation, and the severity of the penalty depending on how bad this overall profile looks. I think there's no harm sharing these ideas, no matter how whacky they seem.. I really have a strong suspicion that Google is penalising based on a backlink profile and not who is linking to you.

I have another website which is a local business site and it has around 80% brand anchor text, the same keyword as in the url (EMD) but it is still ranking #1 however, it has got very few dead links, the link sources are way better. So there is some conflicting evidence - I'm going to be looking at alot of sites now to try and determine how Google are treating these pages in terms of passing penalties through links or site penalties based on anchor text and dead links. Really until more people try to recover their sites, we'll never know.

It all really depends on how many backlinks you have, if you have more than 5000+ then it may be worth your time starting again and building on what is deemed to be a natural link profile with quality sources.

I was wondering the same thing in regards to building back links that my become dead links? I do try to diversify the anchors and only do a steady few a day but this worries me a bit.

There are a number of methods you can check for dead links, one using this free tool here; Backlinks Checker Tool - Backlink Watch just put your domain in and let it collect the profile. You will notice that there are links with missing anchors, when you click on these links (left) the likelyhood is the link has been removed or the site has shut up shop and that's why the tool has failed to collect the anchor text.

There is another method. Go to fiverr and order an OpenSiteExplorer report for you url, then go to; Link Detective and load this report into the detective. It will break down your links by type including any dead links you have. A normal percentage should be 20% dead links, 20% brand, 40% Target keywords, 40% Mixed Keywords.

So depending on your current link profile, if you have a small percentage of dead links but a high percentage of exact anchors then it may be worth removing some links such as blogroll links with exact anchors. However, if you have a high percentage of dead links and a reasonable spread of anchors then it may be more worth your time building a few more diverse backlinks.

If you have a high percentage of both anchors and dead links like me then it may be worth scrapping your site completely - This is the likely scenario if you have been hit badly, otherwise it could take you quite some time to improve your profile and that's not including the fact that Google might actually be penalising these links but that in my opinion is just more speculation.

There is plenty of hear say and little evidence that Google is in fact penalising links from the source. However it has been known that sites that have been spammed heavily with tools like scrapebox get affected by Panda and removing these comments lifts the penalty?? So maybe a contradiction here and perhaps a little evidence to suggest they are classifying the sources of links as spam?

I think even from their perspective it would seem ridiculous. A link is a link, they rely on links, whether in a comment field, web 2.0 or in a forum signature or article they need to count them to a certain extent. It is more likely they are picking up "human error" caused by spammers and link builders in a bid to reduce mass link spam caused by software, blog networks and mass blog comment spam.

I wouldn't advise you rushing over deleting the links you previously built. Don't panic and don't lose your time. Learn your lessons, and focus on building new, better ones. Diversify your anchor text. Look into new link building opportunities.

Some great advice here - thanks!

So if I have a load of dead backlinks, what is the best thing to do? Rebuild them (if it's possible)? Or just focus on building new quality links?

What do you think that webmaster will do for you? If your site is de indexed because of that site inbound links then definitely that site is also de indexed! He is also looking for the same solution like you. So in this case you can't expect any help from that webmaster. Moreover if your site is hit by penguin then you have to wait for at least 45 days, and in between you should change those contents which has bad inbound links.

Really I can't tell you the exact process though I am in this field for some time.

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Rather than wasting your time on changing or removing existing links, it is better to add new links with various anchor text.