the worse "Cake Disaster" I've created for myself (so far) was not removing the cake circle (paper liners) from the bottom of my cake before putting them together. It was a time consuming cake and looked nice when I was done. I put it in the box and sat it on the table. Then something started nagging me, and I didn't know why - I just had the strangest compulsion to "cut into the cake".
I had never cut into a cake that I had made for a friend before. But I opened the box and sliced out a big piece. Thank goodness that I did. I found the papers, realized what a horrible mess that would have been for the recipient, and made another cake.
After that I started using the Crisco/oil/flour mixture, Pam cake release spray, or simply Crisco and flour.