Depends. Have I ever grounded a boat without knowing that it was a possibility? No, not really. Have I ever dragged a keel through the mud? Sure. Most commonly getting in or out of a slip and perhaps touched mud or sand by getting a wee bit close coming into a mark or trying to cut out some distance sailed. Even touched a time or two when gunkholing. That said, never full stop, hit a brick kind of grounding. When charged with navigation duties, I tend to avoid going where the water gets skinnier than draft of boat plus 10 foot margin. There really is no excuse for not knowing where you are.
No. 6. So I take it you have never run aground?
Sounds like running aground to me...