If you check 12.72.020(B ), it says:
The code in question is 12.72.060(I). So it's definitely a misdemeanor. You can find the whole thing online here.
I actually asked a good friend of mine who's a city police officer, and he said, if faced with a citizen complaint, he'd most likely write the citation, release the person, and let the city attorney sort out the rest. Since the law's on the books, they're supposed to enforce it. Of course, they're not *actively* out patrolling the playgrounds, but if good lady citizen called in a complaint of someone lurking around a playground ... it kind of forces the issue. He added that he wouldn't want to take the chance that the person really *was* up to no good, and his failure to enforce it caused harm to come to a child. So he'd err on the side of caution, which seems reasonable from a police officer's point of view (not to be confused with a taxpaying citizen's view, who is being prohibited from using something I'm forced to pay for, but that's a whole different thread LOL).
I agree that it's really sad we even have to think about laws like that. But, they exist, and I'd personally rather skip a cache than spend $3k in attorney's fees, and probably still lose the case anyway (since *any* reason to be there is prohibited).
On a brighter note, this ordinance only applies in the City of Sacramento. I checked the codes of neighboring cities and counties, and they don't have any such thing on the books (yet).