When to turn down a requirement?

That almost sounds ridiculous but there are times when you want to tell a client, "thanks, but no thanks". 

1. You already have too much on your plate and if you take a requirement, the customer will believe you're spending time on it.

2. The requirement is a real "dog" with either, unreasonable skill sets or the pricing is way below market.

3. The requirement is in a area you really don't have experience or knowledge in order to carry on a reasonable conversation with candidates.

There are times that you may want to accept requirements in order to build a relationship or get your name in front of a client, knowing you probably won't make a hit, but make sure to cover your bases and reduce risk, if all goes in the tank.