How should I respond to owners that insist on using their own documents for hiring my professional services and are adamant the documents are "Standard Contracts"?

Remember, there is no such things as a "Standard Contract" and it is imperative that you read each and every one submitted by your clients, so that you know what the client's expectations are and what your  rights and responsibilities are. It is a good idea to have all owner drafted agreements reviewed by your attorney and insurance agent or broker to determine if you are accepting responsibility beyond common law that would apply in the absence of the agreement and if you are agreeing to accountability beyond the protection afforded by your professional liability insurance.