Hi, Nick here.

Roger's at 31c3, so I'll post his statement about that article you might have seen:

Tor hidden service traffic, which Dr. Gareth Owen discussed in his talk this afternooon, is only 1.5% of all Tor traffic. Tor gets about 2 million users per day total.

The researcher ran a set of Tor relays for a six month period, and recorded how many times somebody attempted to look up a hidden service (this lookup is one of the steps in visiting a hidden service). Then at the end of that period, he scanned the hidden services he'd learned about, to find out what sort of content was on them.

Dr. Owen's data shows that there's a lot of churn in hidden services, so nearly all of the sites were gone by the time he did these scans. His graphs only show data about the sites that were still up many months later: so his data could either show a lot of people visiting abuse-related hidden services, or it could simply show that abuse-related hidden services are more long-lived than others. We can't tell from the data.

Without knowing how many sites disappeared before he got around to looking at them, it's impossible to know what percentage of fetches went to abuse sites.

There are important uses for hidden services, such as when human rights activists use them to access Facebook or to blog anonymously. These uses for hidden services are new and have great potential.

PS: Law enforcement agencies use Tor to stay anonymous while they catch bad guys. Law enforcement agencies use and run hidden services, too.