Among them: J. Michael Straczynski, author of DC Comics' upcoming sequel to the non-canon Superman: Year One.
During the discussion of the company's forthcoming series, Straczynski revealed that Superman will have the opportunity to have sex with a human, but totally blows it.
[Straczynski] related that in the upcoming book, Clark has spent his whole life unable to have sex, and related a scene where after fighting the Parasite, Clark gets depowered, takes off his suit and heads home to finally have a sexual liaison with his super-hot neighbor Lisa.
As Straczynski explained, "When he was young, Pa Kent told Clark that he'd probably never be able to engage in sexual relations due to the possibility of losing control over his powers." Clark initially passes out, but starts to get intimate with her after waking up again.
Soon afterwards, however, his X-Ray vision suddenly returns, and he becomes frustrated that he slept through his seemingly only window to safely have sex.
While many people, male and female alike, have fantasized about Superman as a sexual being, it's probably best he steers clear of intercourse with humans. We humans are strong, but are we strong enough for the Kryptonian's "super sperm?"