Everybody (and not just Software Engineers) should keep this quote from Francesco Guicciardini (https://en.wikipedia.org/wiki/Francesco_Guicciardini) always in mind when dealing with people/companies/world;

To get a reputation for being suspicious and distrustful is certainly not desirable. Nevertheless, men are so false, so insidious, so deceitful and cunning in their wiles, so avid in their own interest, and so oblivious to other's interests, that you cannot go wrong if you believe little and trust less.

-- No. 157, Maxims and Reflections (Ricordi)