I'm sure. I, however, have had dealings with mastering engineers where I felt they were trying to pull a fast one on their clients and mistakenly thought that I as a fellow engineer would find it amusing.
I have also had a short thesis that I wrote stolen by a fellow mastering engineer whom I regarded as a man I could trust, and used commercially.
In short, mastering engineers are not all sweetness and sunshine.
If you re-read, you'll notice that I was never calling their competence into question. The music business is a very competative and testosterone driven industry and it is not at all uncommon for people in it to be very unkind to each other and / or to use each other to terrible advantage.
Some engineers are better than others. Some are more honest than others.
They are not all the same and working with one mastering engineer can work out well for you while working with another might not. It's all about building up a network of contacts you can trust, work well with and rely on.
I see absolutely no harm though in pointing out a few of the things worth watching out for. Like car mechanics, it is not unknown for mastering engineers to make work for themselves that is, shall we say, superfluous and reductive.
Do you mean that I'm a mixdown engineer and should shut up? If so, then with respect you do not know what kind of engineer I am.
As it happens I am a good mastering engineer with some production credits to his name among other accolades, and I am fully aware of what happened to the completed masters. Some of them actually got pretty respectable reviews in mainstream newspapers.
I also know that a few of my fellow engineers are more interested in feathering their own nest than sending the lift back down for the people coming after them. Since at the moment I am in the happy position of not having to rely on sound engineering to make my living and have little intention of doing so again, I don't see much harm in being the prestidigitator who reveals the tricks.