Earlier quoted context omitted.
I suspect they do a good job at a technical level, but they have interests in advertising that are at odds with my privacy interests. I also have no way to know if they are doing Dark Nefarious Things.
I totally agree with you. From your initial comment, I got the impression that you were claiming that closed source software could not be excellent..meaning secure. By the way, I'm a big GPL/free software nut. However, I understand the place of closed source software, and under the right circumstances, it can indeed be excellent.
Open Source can be bad, in terms of quality. Closed source can be good, in terms of quality.
Security is an interesting case where I don't believe that you can be trustworthy and closed. Could the code be good? Yes. Can I validate in any meaningful sense that it doesn't violate my expectations? No.
Of course it's possible to have obfuscated malicious behavior in Free/Open Source software. But, there is at least the possibility of descovery of such defects. With closed source, there isn't.