Clarke was a gay guy and had some younger lovers in Sri Lanka. I have seen no evidence or even rumor of children. I have a hard time linking him to any immorality.
PBJ, I'm with you on your read on Heinlein, even though I still love his work, bit of a narcissistic kook. I believe Clarke was not a child abuser. If I find new evidence in the future so be it.
Hubbard, I think may have had a screw loose, but again haven't run into anything pointing towards sex with children.