Correct, No BM expect his reputation to be destroyed by his managed SCAM projects. So there are much be careful to go negotiate with project teams even though BM's also can lose his management fee if teams will scammer. I see some reputed manager deceived by team management.
Yes, that is clear and also very often happens to experienced BMs, because that is not what they want, but rather the project team's intention to deceive everyone including BM in which all project participants will become victims.