I personally think that stealing wifi is a less bad offense, compared
to, say, stealing welding rod.

If wifi is completely unsecured, from my own ethical standpoint, I do
not consider it stealing at all. I know that the law may disagree with me.

If wifi is protected by WEP, I consider its use to be stealing, but
not as immoral form of stealing as taking a GPS from a car or some
such.

i