> Management consultants nearly always have a conflict of interest though (i.e. the preoccupation of consultants is almost always "sell, sell, sell" rather than "help the client make money") due to the nature of their work and their short-term contact-based engagements mean they rarely have to stick around and deal with the messes that they create.

Not my experience at all. If you show value to the client and you build a trust relationship then you enter into a relational mode that is fruitful for both sides, and you skip/streamline all the tedious commercial topics (RFPs, competitors, beauty contests, the purchasing department demanding a 3% discount...). On the other hand, if you want to milk the cow dry then you end up on a very transactional relationship and you need to start cold selling from scratch after every project, which takes a lot of effort, time and energy.

In any case, again, the conflict of helping the client vs. overselling is hardly a consultant-specific topic; I’d say the smaller the shop, and the closer the ownership to the sales team, the more pressure there will be, in general. Case in point: the actual doctors that overprescribe opioids!