The below article offers a good perspective on confidentiality agreements. In summary if the individual is not familiar to you and poses a competitive risk or if you are in the patent process an NDA/CA is appropriate. If the individual is a professional advisor (Attorney, CPA, Business Broker, Venture Capitalist, Angel Investor) it is generally innappropriate. Another consideration is if they are coming to you a written agreement is more appropriate. If you are going to them it is less appropriate. An experienced business broker will ALWAYS secure an NDA/CA from prospective buyers or discuss with you in advance of releasing any of your confidential information.
When is a Non-Disclosure Really Required?
Entrepreneurs often get the advice from their lawyers and friends to always get a Non-Disclosure Agreements (NDA or CDA) signed before disclosing anything about their new venture. Most investors and startup advisors I know hate them, and refuse to sign them. Who is right?
Let me try to put this question in perspective. If you are totally risk-averse, then push to always get signed NDAs. Chances are the most experienced and valuable contacts will choose to pass.