I'll just throw this into the soup:

Many years ago I built a Goldberg Cub, after a while it met its expiration date.

A year or two later, I built another one. I used the same engine, same battery location, etc. and I didn't bother to check the CG. (Yea, I was Young and stupid and I figured since everything was the same the CG would be close enough)

Well I could never land that plane properly. No matter what I did, it always came in like a dart and wouldn't slow down.

Then, one day I did a spin with it, and it wouldn't spin - it just sort of spiraled down. Now I KNEW this was a sign of being nose-heavy, so I checked the CG and sure enough, it was nose heavy.

So I moved the CG back to the proper range and from that day on, it floated in gently on landings.

Since that time I have witnessed this on several of other people's planes. So now, when someone tells me their plane lands hot, the first thing I say is, "Check your CG"