Since were talking about spinning, I'll share a unintentional spin experience. I was helping a student with maneuvers for his CFI Initial in a C152. He preformed a powered on stall, felt weird, didn't look right. I took the controls pitched up around 30 degrees had everything coordinated, watching the speed drop, waiting for the stall.
The nose broke violently straight over, violent enough to rip our headsets off and throw them to the back of the plane. The plane went into a power on inverted spiral spin\dive. Took about 1 turn before I was able to retard the throttle. I put in opposite rudder, and it took 3 more turns before it broke the spin. Pull out was just under Vne. I was very careful on the recovery to not over stress the aircraft at that speed, and that close to the ground. Recovery was around 1200 AGL. My student asked me to let him know next time we were going to spin. I let him know that it was unintentional.
I could tell there was something seriously wrong with the aircraft the way it entered the spin, and handled during the spin and recovery. I was talking to a 35 year CFI about what happened, and he asked me to not ground the plane, he wanted to take it up to see what I was talking about. 15 minutes later he came back, grounded the plane, and said he couldn't stall it without it trying to spin on him. Owner of the school saw we grounded it, decided to take the grounded aircraft up, because we didn't know what we were talking about. Came back a few minutes later pale white, almost impacted the ground.
Mechanics found that there was a structural failure in the empannage, it was being held up by 1 bolt. You could see it flex by lifting up on the tail. The failure points had some slight corrosion on them, so not really sure when the initial damage occurred.
The aircraft was problem prone, high air-frame time, I usually changed my schedule to not use it. This flight I happened to not be able to change the schedule and didn't want to cancel a lesson with a student over my distaste for an aircraft. Least to say I refused to ever fly that aircraft again.