Good idea / bad idea

If you ever watched the '90s cartoon show Animaniacs, you probably saw a segment in the program called "Good Idea/Bad Idea." If you've never seen Animaniacs, here's a two-minute compilation of some of the Good Idea/Bad Idea sketches (courtesy of Youtube). Hilarious!

Now then: in the publishing world, there are very often scenarios in which what would otherwise be a great idea is actually a terrible idea due to one or two crucial detail(s). As part of your (and, frankly, my) continued education...