The thumbs up/down feature could really use a rework.
Currently, the incentive for a user to leave a thumbs down on the profile of a user they had a negative experience with, is practically zero. Why? Because the other user retaliating with a thumbs down on your own profile is practically guaranteed, and you can't do anything about it.
The current system inaccurately represents the actual reliability of a user. Not only because of the above, but also because there is no way to distinguish whether a user has only ever bought modules, or has also sold modules. Buying a module carries much less responsibility than selling a module.
I have yet to come up with a concept that would work better as MG transactions are based on mutual trust between users, rather than having MG be the middleman, which would not be a solution either for various reasons. Perhaps we can come up with some ideas as a community.
(On a side note, are these suggestions ever being read or considered? I have posted several suggestions and have yet to see anything come from it, be that a reply or implementation of some sort.)