When encountering an individual that lacks intelligence or common sense, I attempt to assist them. I often find a way to expose them to the things that will improve their intelligence and common sense so they are not seen as "stupid" again.
As an individual that deals through strategic thinking, I find that the only "stupid people" are those that judge others as "stupid" and do nothing to correct that assessment.
Limited knowledge and experience is no reason to declare anyone "stupid".
The Forrest Gump author, Winston Francis Groom, Jr., said it best - "Stupid is, as stupid does."