https://www.npr.org/2012/12/06/166666265/why-some-homeless-c...

A specific account of sexual abuse in a shelter here:

https://abcnews.go.com/Politics/wireStory/mayor-orders-probe...

There's plenty of reporting on it. As with all news, it's tough to get realistic accounts of what's going on in shelters because a lot of the people being asked are involved with shelter administration, so obviously there wouldn't be as much emphasis on the bad living conditions. Getting more info from actual homeless people would be helpful, but obviously the entire point is a lot of them are battling substance abuse issues and/or mental health problems, so there are complications on getting decent information out of them.