I'm genuinely interested to know how you would know if an airplane was built by bad engineers, and which ones you personally consider to be safe/unsafe. I think I would go on any aircraft if the pilot was good, as the basic principles of aerodynamics generally result in stable and predictable controls. Putting a twist in an elevator cable is probably the least obvious way for a bad/malicious engineer to make a good airplane dangerous. But I don't think any layperson could have predicted the Boeing 737 MAX 8 failures, as they were caused by invisible problems in the computer control systems; the physical appearance of the aircraft doesn't look too unusual.