Being in the index isn't very meaningful. Very little of our spam-fighting/ranking prevents sites from showing up for "site:" queries, because in general we think that if someone is intending on going to a domain directly, the only reasonable thing to do is to show that domain.<p>Unfortunately I don't have a better way of assessing it to offer. Internally, we often look at impression-weighted precision as a metric, but I don't think there's an easy way we could expose that to you.<p>A more reasonable thing to do would be to take a sample of DDG's query logs, scrape the results from Google, then see what percentage of Google's results come from your spam domains, but that requires sending a lot more queries to get any useful data.