The British Standards Institution has published a new standard, BS 8538, Specification for the provision of services relating to the commercialization of intellectual property rights. A copy can be purchased online.
Their press release mentions that when it comes to service providers, "some take advantage of inventors either inadvertently or intentionally". Service providers include commercial companies, and inventors' clubs. The standard is 24 pages long.
The standard covers the topics of integrity and competence; transparency regarding fees, costs and finances; confidentiality and the disclosure of information; declaration of interests and conflicts; and a procedure for complaints handling.
What I didn't see was a mention of unfairly high fees or of unfair contracts. I have seen contracts by invention promoters where what the inventor had to do was carefully specified, while what the promoter had to do was left vague, where high fees were expected both up-front and as a royalty, and where the contract could only be terminated if both parties agreed. The moral is to "shop around" and to see what free help is available, such as from us and from the Patlib libraries).