I recently answered a similar question. Here is what I wrote:
Consider that McK is running several thousand engagements in parallel at any given time and is highly decentralized. Of course, there will be bad apples and bad players, which in turn leads to some bad and shameful outcomes every now and then. And it is exactly those that are reported on in the media (rightfully so). However, this is far from the norm and in general, the internal control mechanism work and as I read will be improved.
Is this the norm? Hell no. As said, the firm runs tens of thousands of smaller and larger projects every year and over the last few years a number of scandals emerged. But it is en vogue to bash McK, for which the firm also has to take some blame because of the secretive nature of how it presents itself...
The people I worked with (some of the nicest friends I ever met) and the experience I made and discussed with my peers while working there were nothing like that.