I have personal friendships with many of our countries top inventors, and I have made a point of studying how they and many other inventors operate. Examples being Barron, Damadian, Ellion, Greatbatch, Hougen, Hyatt, Lemelson, Levine - to name just a few. All of whom are multi-millionaires and a number of whom are worth tens or even hundreds of millions.
I have noticed that there are two basic types of inventors. One is a one or two shot type and the other produces many inventions, often in more than one discipline. By one shot I mean those who produce in a fairly narrow area, maybe more than one patent but not diverse. In my experience the really good inventors produce many more inventions than they can afford to pursue, and they are very selective in patenting because of the time constraints of marketing the inventions. Some inventors are really one shot types, and if they have moderate success, but lack the skills to really succeed they often continue their careers offering engineering or marketing services to other inventors. Those who are engineers generally are good service providers. But those who tout themselves as marketing people are usually bad news. A few do very well in this capacity, but most resent the fact that they did not have what it took to succeed as an inventor. And the reality is that those who resent their situation are really bad news for inventors. When selecting service providers it is wise to be on the lookout for the would be inventors who lacked the ability to either be prolific inventors or to be really successful in marketing their inventions. These are the ones who frequently offer their services to other inventors, trying to make ends meet. They are the same people who frequently try to con inventors into making them a co inventor when in reality all they are offering is engineering services which do not really qualify them as an inventor. Those inventors who do really know their stuff are not out marketing their services to others, because they are making enough money that they do not need to offer to sell their services, and they are far too busy with their own ideas. That is not to say that there are not times when an inventor should partner, especially if they are launching their own company. But in general, it is a mistake for an inventor to partner with anyone who has illusions of being an inventor. And if an inventor is going to partner they need to look for people who have a track record of success, not with another inventor who could not hack it. Selecting such is a classic example of the blind leading the blind, and a certain recipe for failure.