1. Most sites get a Google warning after creating spam links
Matt Cutts says that there are two different situations when someone wants a link removed:
“Situation #1 is by far the most common. If a site gets dinged for linkspam and works to clean up their links, a lot of them send out a bunch of link removal requests on their own prerogative.
Situation #2 is when Google actually sends a notice to a site for spamming links and gives a concrete link that we believe is part of the problem. For example, we might say ‘we believe site-a.com has a problem with spam or inorganic links. An example link is site-b.com/spammy-link.html.’
The vast majority of the link removal requests that a typical site gets are for the first type, where a site got tagged for spamming links and now it’s trying hard to clean up any links that could be considered spammy.
2. If you get many link removal requests, you should check your website
Some people get link removal requests although they did not add artificial links to their websites. If you get many link removal requests although you did not participate in link schemes, you should check your website:
“It’s not a huge surprise that some sites which went way too far spamming for links will sometimes go overboard when it’s necessary to clean the spammy links up.
The main thing I’d recommend for a site owner who gets a fairly large number of link removal requests is to ask ‘Do these requests indicate a larger issue with my site?’
For example, if you run a forum and it’s trivially easy for blackhat SEOs to register for your forum and drop a link on the user profile page, then that’s a loophole that you probably want to close.
3. If your website hasn’t been exploited, you can ignore link removal requests
If you haven’t been spamming and if you’re sure that your website hasn’t been exploited, you can safely ignore link removal requests:
If the links actually look organic to you or you’re confident that your site is high-quality or doesn’t have those sorts of loopholes, you can safely ignore these requests unless you’re feeling helpful. […]
This is a great example of a well-maintained forum, and as such I agree that you’re doing the right thing by ignoring link removal requests.
By SEO Costa Rica Profiler