I have been involved in the accounting and due diligence on several acquisitions in the 100's of millions and a few in the billions. If the executives want to buy a company bad enough they will downplay the findings and make the acquisition happen. Any time you hear about write-downs or other accounting issues after an acquisition rest assured management was fully aware of it. The auditors that look at this are good and will find these things.
The problem is the auditors also want repeat business so they will say what the executives tell them to.