When I was an apprentice in a small company, ...

my boss told me that his company would never ship release builds, because the "evil optimization option" is responsible for breaking his code.
My first thought was that it wouldn't make any sense at all. The default option for code optimization is always set to zero.
After investigating his code, I found out that he didn't care to properly initialize his variables. The default compiler option for debug builds did implicitly initialize all variables to zero. After that I've confronted him with the fact that implicit null initialization does not conform to the standard of C and C++. He didn't believe me what I was saying and he was questioning my knowledge about C and C++. He refused to fix his code to this day, so he keeps building his libraries and applications always in debug mode.
Bonus fact: He would never build 64-bit applications, because his serialization functions do get incompatible with exisiting file formats.