From MarketingProfs.com:
Logos: What Makes Them Work (Part 1 of 2)

An idea I thought I was the last to hold on to:

1. Black and white first

Good logos are designed in black and white first. Color comes later. By the same token, logos should be judged in black and white first, then in color.

By evaluating the black and white version first, you get a much better idea of the shape, design and readability of the logo. Good design stands up well in black and white. Lousy design does not. Lazy designers know that bad design can be camouflaged by color. A logo shouldn't rely on color for its appeal, uniqueness or ability to be recognized.

If you're hiring logo designers, insist that the first presentation come to you in black and white. If they don't get it, fire them before they get started.

That pretty much says it all. It seems recently clients do not want to listen to this. With the immediacy of the web and the computer and all that has been desktop publishing, clients think they need to see color variation initially while looking at design options. It is always a crutch, always gets in the way and always makes the outcome worse and take longer.