First, downvotes. The point of them is not to punish users but to simply gauge post quality. The description when you hover is "This question does not show any research effort; it is unclear or not useful." Sometimes naive questions really do fall under the lack of research criterion, e.g. someone should really know that their moldy food is not good to eat. Sometimes they're also very unclear, not giving enough details to really provide an answer. But sometimes they're totally fine, and might even deserve an upvote ("This question shows research effort; it is useful and clear.") It's up to you to decide if either applies to a given question.
Beyond that, all we can really do is do our best to make sure they're answered in a way that really covers the underlying issues, not just the specific situation. Often this means that it's good if someone learns the rules of thumb about the danger zone, rather than just being told that their current food is unsafe.
Note that since these naive questions are pretty common, they're also often duplicates. See Are our food safety canonical questions being used well? for some discussion on how we should approach this. Note in particular that people generally like the idea of closing as duplicates (possibly with a comment tying things together), but do sometimes want more thorough duplicate targets than necessarily exist. If you want to try to help in that regard, posting and self-answering some of the questions Joe mentioned in his answer (or other things in that vein) could be useful, as could doing a bit of a survey of past closed questions to see what's really important to cover.
