Backlinks Dropping Like Flies

I have a web site that has been doing the google dance for about 5 months now. It will be in the rankings for 2 weeks and then lose its ranking then come back for a little while. anyway, google has dropped off about 3,000 backlinks it did have and completely discredited them.

The site was showing 6k+ backlinks in webmastet tools and within the last week it has lost about 3k+ links and only shows about 2862 links. Can anyone point me in the direction on why this is happening? Used scrapebox, senuke and bought some xrumer blasts.

I thought that if google credit you with a backlink from a site it would stick for the life of the site, or am i wrong?

Some backlinks are losing their potency, such as forum, profile, and blog commenting links. I too thought that once a link is there, it's there. Google has the power to discredit previous link strength, but I don't know about removing links.. anything's possible. See this thread:

http://www.blackhatworld.com/blackhat-seo/link-building/255833-important-info-regarding-googles-algorithm-change.html

You could have been seeing recent comments links, and also blog owners may have been unapproving your comments. If you bought xrumer blasts, they may have been done poorly and either edited or deleted to remove your link.

This type of link building is NOT permanent, thats why it needs to be done all the time to keep google happy feeding it fresh links.

google keeps indexing web pages and once the link is deleted its off googles database too your xrumer blast links probably have been deleted by the blog,forums mods.