'This code was already worked on and we paid for it... it can't surely be that bad'
If you deliver something broken it's better than delivering nothing... you'd be surprised how often we get 'We'll improve it later' compared to 'You didn't deliver anything?'
But it wouldn't even take much effort to fix. It's not like all of it has to be rewritten or anything. And once my contract ends, they're kinda fucked - they don't have, and aren't going to be able to hire, anyone with my C++ and multithreading/concurrency expertise. If I were in their shoes, I'd take my advice like word of God while it's available, and try to learn to write better C++.
'This code was already worked on and we paid for it... it can't surely be that bad'
If you deliver something broken it's better than delivering nothing... you'd be surprised how often we get 'We'll improve it later' compared to 'You didn't deliver anything?'