"One very good idea for competing with google would be to replicate google a few years ago, just with the necessary extra spam protection."
Google actually did that for their 10th anniversary: they set up a copy of their 2001 index with the old ranking algorithm and old UI and let people play with it. It was only up for a month (there's a heavy maintenance cost for playing with code that old), but if you image search for [google 2001 index], you can see a bunch of screenshots.
I just played with it down to about page 6 of the image results (now there's a feature that didn't exist in 2001...), and didn't find a single query where I preferred the results & UI of then over the ones now.
I feel the same way. These days, junk results are the norm. Google Instant was a funny product launch to me because it sort of proved that the results aren't good anymore and making it faster to search is a stop gap.
One example off the top of my head: If keyword doesn't exist in the page I'm normally not interested, even if other pages links to it by that keyword.