Believe it or not, there are times when you should decline the money. In the case of larger investors, you should perform your own due diligence on the potential funder. What has been the experience of other companies they have funded? How active a role did they play in the management? If the funding was incremental, did it come on time and when promised? Did they add value to the company and its mission? If the funder refuses to give references, run—do not walk—away.
The reverse of the big funder is the couple on a fixed income who love you and want to put their last savings in your company. Do not take that money—it is unethical, ill-advised, and always more trouble than it is worth. Some investors just are not right for your company. Learn to recognize them, be respectful, and let them go.