Keywords in Google.

I keep reading on here and other sites that Google ignores meta tags or ignores keywords etc.

But I also read that no-one really knows what algos Google and the other SEs use.

So how do you know that Google ignores Meta Tags ?

Do you have any REAL proof or is it just supposition ?

I also notice that quite a few people who complain that their sites have dropped off the edge of the Google world don't seem to bother very much about these tags.

Could there be a connection ?