McIntyre: Scanning for assembly code in Free Software packages

But in any case, if you re-write incomprehensible code, you are almost guaranteed that the result is code that doesn't do the job that the original did, because you don't fully understand the problems that the code is solving.

You probably understand the more obvious problems, but the subtle problems and corner cases will bite you.

That doesn't mean that you should never re-write something, but rather than when you do so, you need to recognize that you aren't going to get it right in the first try, and you need to be sure that the value of having the new code (leaner/faster/better documented/etc) is greater than the effort to re-write the code AND then debug the code after it hits the real world (including whatever damage the bugs can do)