Examples of Bad Logos
Before we talk about what makes a great logo great, let's take a look at a couple of bad ones first.
The IRS Logo: As Complicated As Their Tax Forms
The Internal Revenue Service (IRS) brands itself in many ways but their logo is not one that most people recognize.
The IRS logo is all black: a one-color logo is less memorable than one with at least two colors and their icon is too complex.
If you study the IRS' logo you will see a branch, scales, and an eagle shape (in the right side) that blends into the scales. Of course, someone else might look at this same logo and see something entirely different like a feather and a ghost.
Keep your business' logo simple because people are not going to study it for long. You need a logo people can immediately process and comprehend. If they do not get it with just a glance chances are very good that they won't remember or recognize it later (unless you write your company's name across your logo.)
On balance, the IRS logo is more like a "can you see a bunny hiding in this image?" puzzle than a logo. Unless you are like the IRS and can hunt down your clients to make them pay, do not try and pull off a logo as "creative" as the IRS'.