Prison is not "soft" but is "as bad as you could possibly imagine", the outgoing chief inspector of prisons in England and Wales has said.
In an interview with the Guardian, Nick Hardwick said conditions in adult prisons had deteriorated over the past five years.
He also criticised the detention of asylum seekers and the "failure of empathy" among civil servants.
He leaves his post on Sunday, having decided not to apply for another term.
Mr Hardwick told the Guardian his job was a role that should not be done "for too long because you get used to things you shouldn't get used to."
He described some of the conditions in prison as "disgusting", with prisoners living two to a cell, eating meals sitting on the bed next to an "unscreened" toilet.
"Things have got worse, and I think they would have been even worse were it not for us," he said.
In his final annual report released in July, which said that prisons in England and Wales were in their worst state for 10 years, he noted that one staff member at Wormwood Scrubs said of the cells: "I wouldn't keep a dog in there".
In that instance, they found that toilets "were filthy" and inadequately screened, broken windows, and cockroaches.
Mr Hardwick also told the newspaper that children who are locked up in young offenders institutions are being failed.
"These are our children; we should be moving heaven and earth to try to make a difference and we don't," Mr Hardwick said.
He said it was "bonkers" that "our most troubled children" were put "in an institution with loads [of others] just like them" and said they should be put in smaller units.
Referring to one instance when he was approached by a boy in an institution, he said: "I said, 'What can I do?' and he said, 'I want to go home to my mummy."
Mr Hardwick also suggested that locking up asylum seekers is an abuse of power.
"These people haven't been convicted of anything, and they're detained on the say-so of a relatively junior civil servant," he said.
On policymakers, Mr Hardwick said there was a "lack of imagination and failure of empathy".
"Too many policymakers do not ask themselves the crucial question: 'How would I react if I were in that situation, and why are people in prison in the first place?'" He said.
Earlier this month he told BBC Two's Newsnight programme that prisons have grown ''a lot more'' dangerous.
Mr Hardwick has been appointed chairman of the Parole Board of England and Wales, succeeding Sir David Calvert-Smith.