MattB,
I currently work with a company that tries to offer "full service" services to and designed to assist the individual inventor. Again, do your research and due diligence and be skeptical but not adversarial. Even legit companies probably have some procedures in common with the scam companies, that is how the scam companies convince those unsuspecting victims they are legit.
For example, at the company I work for there are 3 divisions. The first contacts the inventor after the inventor expresses interest in our services and requests properly enabled invention disclosure. At that point, the inventor can choose to have a patent search and opinion performed by licensed practitioners or a combination patent search and opinion along with a basic market research report related to the general class of commercial goods. We always do a patent search and opinion before offering follow-on services for 2 main reasons: 1) it allows the inventor to make an educated decision based on cited prior art, and 2) we try to be conservative in our opinions so that if we give a positive opinion we can feel comfortable that a patent on the invention will issue. Of course even if we give a negative patent opinion many times the inventor will disagree with our professional opinion and want to move forward anyway. If it is a close call and the inventor is fully informed about the chances of success we may move forward with patent prosecution. If we do not feel that an application stands a decent chance of success we continue to reject the invention and follow-on services and allow the inventor to find another provider.
Once an invention disclosure receives a positive opinion, the inventor can choose to have legal only, marketing only, or legal and marketing services performed. We offer a flat fee paid upfront for the services to an inventor can properly know what the total amount needed to prepare and prosecute an application and/or receive marketing services. The patent prosecution is performed again by the licensed practitioners and the marketing is performed by industry professionals having contact with others in that or similar industries. We always let a potential client know that the chances of success are small, but we have had numerous success stories and various products have been licensed. Although marketing is not my area, one point where many inventors are unsuccessful or where the marketing efforts stall is related to the inventor feeling that our company will be successful and basically quit all work on their end. Successful inventors continue to self market, try to get prototypes, and do anything else that will help them be successful.
Just some thoughts from someone kind of in the business, take them for what they are worth and good luck.