I hate to reject code technically works, but comes with technical debt (may break in another compiler/OS, doesn't follow naming/coding style, lacks tests/documentation, etc.) I can't nag to much "fix this, and that, and that, and change name of that", but OTOH if I don't then I'm the one left with the technical debt.

On few occasions I've spent more time on integrating someone else's changes than it would take me to write it myself.

Still, of course everybody learns and has to start somewhere, so I welcome pull requests.