How Do I Spy On Competitors Backlinks...Just Ones That Google Knows About?

I want to spy on my competitor's backlinks and do some reverse-engineering.
I also want to see how many of my own backlinks Google "Really" sees for my sites.

Google's "link:" command only shows a small amount of backlinks, so Google
does not let you know all of the backlinks that it has found (It's probably an
algorithm thing).

Forget about Yahoo Site Explorer! That only shows me how many links Yahoo
has on me.

Are there any sites or tools that will let me see ALL the backlinks that Google
knows about, or at least more than the "link:" command does?

Do you think it's correct or a true statement that if you want to rank for Google,
then one of the things that matters is how many backlinks that google indexes?

Google webmaster tools now does an excellent job of showing you your own links for your sites. However you cannot view a competitors links through google.

The best tool I've seen for this is "SEO Spyglass".

They have both a paid and free version, the free version will only let you see and analyze 1100 of the links but it's still good.

The paid version scrapes data from heaps and heaps of sources and is the most comprehensive backlink checking tool I've ever seen.