karoshi asked

“For each level, what is the average time a site stays indexed (if done intelligently)?”

For this question I like to use this Illustration:

On a scale of light to dark, if your site operates in the “A” area, there’s a good chance you’ll get banned. But if you stick to the operating in the “B” area, you can keep your sites indexed indefinitely.

To answer your question more directly, it’s not uncommon to have sites at all the levels stay indexed. In fact, unless you are testing the limits of a particular spamming technique it’s rather uncommon to receive a surprise bann. You pretty much know which sites are likely to get banned and which are more likely to stay.

If you dress your spam sites up nicely, even the sites on the bottom level can stay indexed forever.

One of the more interesting thing about having a large number of sites that employed different techniques to rank and get indexed is watching the ebb and flow of Google’s search engine algorithm. The factors that rank a site don’t change, but their weightings fluctuate pretty wildly. Sometimes you’ll have sites that had no traffic for years spike upwards for no apparent reason.

It’s always strange getting commission checks on 5 year old links that hadn’t generated money in years.