I suppose it happens to all of us... and indeed it happened to me too....
I had some beige yarn with no ballband (it was wool but I had no idea what percentage) that I knit into a moebius bowl.
Actually it was a moebius band. I just picked up the stitches around the band,
crossed from one side to the other where the moebius crossed, and knit the bowl like a hat.
I did the same with the green one with 15 less stitches.

I threw them into the washing machine to felt. The green shrunk to less than half its original size in minutes; the beige was in for 1.5 hrs and wouldn't felt! Grrrr...
The beige is now in the trash; the green is full of carmels.