How the SEs count links

[theJack]

Usually, when I use the market leap tool to check link popularity, all of the search engines return similar amounts of links to the sites. Lately, a couple sites I've researched have had abnormal amounts of varying links, for instance (this site is well established, and I don't think time has anything to do with this):

Allthe web Altavista Google Hotbot MSN yahoo
1,030 1,060 163 5,629 5,613 1,710

At first I thought something was very wrong, but looking into it some, it appears some of non-google SEs count image links. While I'm pretty sure google does not count them. The site in question is a large, commercial site that I'm pretty sure uses alot of banners. That might explain part of this, but it still seems like a large difference in link counts.

Does anyone have good answers on what triggers the different search engines to count links?

[awall19]

they all just show slightly different backlinks...google is showing garbage right now.

[Searcher]

Different search engines must have many different amounts of pages in thier databases and also different pages, and this must count for different links also.

[I, Brian]

Search engines also index to different depth levels, and can be fussy about what they will actually class as a link. For example, Yahoo! Slurp apparently likes to index links on static pages, but pays less attention to links on dynamic pages.