I don't have anything remotely resembling a do's and don't's of voting, but my voting pattern closely matches yours.

My voting is somewhat asymmetric, in that I will upvote nodes that are OK though not necessarily superb, whereas only nodes that I strongly disagree with or dislike will get my downvote. (Clearly more upvotes are cast than downvotes, since the $NORM consistently hovers around 10, so I suspect that such asymmetric voting is common.)

I never downvote a node on the grounds that it is a "stupid question" or "ignorant question". No such thing in my book. (A question can be asked ineptly or carelessly or inconsiderately; that's another matter.)

Update: I put questions like this one in the "inconsiderate" category, because the questioner obviously has not done what I would consider to be the absolute bare minimum "due diligence" of learning basic Perl. I may still help such questioners, but I always downvote such nodes.