Saw several cases of hand propping going bad.
A guy propped his 180 on skis. It got away from him and was going in a big circle, gaining speed until it hit his floats stored along the edge of the lake, bounced over and hit his pickup. Pretty much put him out of business for the rest of the year.
185 just out of rebuild. Handpropped and got away, roaring across the road at full throttle heading to the airport maintenance building. The 185 became airborne just before hitting the building....it went back into rebuild.
A guy hand propped a 206. No one knows for sure what happened but he thinks he must have slipped on the icy ground. When he became away again he was lying under the running airplane. He body was parallel with the fuselage, his head in line with the prop arc. He had the moxy not to jump up and scooted out from under the prop. Luckily for him he had big tires on him 206 or it would have been very sad. I was sent to this call for first aid. He had a big laceration on his forehead probably from the prop.
Propping isn't bad, you just have to do it correctly. A friend always hand propped his Cessna 180. He had a refined technique, his engine always started with a gentle flick of the prop. The reason he did this was because he was flying into the bush all the time and he wanted to know for sure his engine would start. For him the electric start was his back up.
We were going to prop the B-17 one morning to see if it would work but none of us were tall enough.