When I go through my links page - or my site-wide links section, I tend to find out that other websites that I've link exchanged with in the past - and were supposed to keep my link up, actually removed my link without notice.

Why do you think webmasters remove links without informing one another?

To gain one way link benefits and decrease outbound links..!

The reason why it is recommended to build a backlink checker script..which we have for our inhouse sites..and it works wonders for us.!

I experience this a lot. Exchanging links is really tricky. There are many irresponsible webmasters out there. So I often check my backlinks and remove links that no longer reciprocate.

Well that is really unethical... but we don't have total control on our link exchange partners.

You can write a letter to the webmaster and ask for reason, but it really happen usally and don't expect for any good answer.

Well inform them or ask them. Then if they didn't cooperate you should take an action and also remove their site to your site.

I have also experienced this when I do exchanging links with other sites. Some of them have deleted my links on their site or add a nofollow value on my link without informing me although their link is still live on my site. To make it professional, I sent them an email asking why they deleted my link but I got no response from them. So I just deleted their link on my site.

yea...

i encounter this before. May be remove our links with some reason!

Your best bet is to have an automated script that checks the links and emails the site in question to notify them that you cant find the link and can they tell you the location. If they don't reply, you pretty much have your answer. take down their link.

This do happen, that's why its good to always have a record and check once in a while if your partners are still linking back to you.

They do it so they are getting non-ceciprocal inbound links. You can manage your links both ways using IBL Builder.

in short, they do it because they can

lots of shady webmasters out there. You should monitor your links regularly.

Not all webmasters a shady, but there are a lot of them.