A recent newspaper story, one that can probably be duplicated in a half dozen states every year. A middle aged man and his wife invite a mutual acquaintance to live with them. The other woman, financially challenged, becomes sexually involved with the man, and the woman aids and abets his sexual assaults by supplying drugs for them all.
The couple were arrested after the captive housemate managed to alert police about her situation and the sexual abuse that had continued for more than 3 years.
These kind of crimes attract more attention than most sex offenses. It send the message that all sex crimes are equally gruesome and tragic. They aren't.
But the other point here is that there are some offenders who are beyond our current capacity to treat effectively. The man in this case had two prior sex offenses. He was already on the sex offender registry. No matter, where his deviant will and his wife's complicity are concerned, there is seldom enough eyes and ears in the population to prevent such crimes.
While treatment for these two may provide little hope for success, that's no reason to doubt the valuable contribution that sex offender treatment has on the majority of people convicted of lesser crimes.