I'd rather reverse engineer spaghetti code than a spaghetti Excel spreadsheet.

Most probably because you do not know Excel !? But for someone who do know well Excel and understand finance concept it'd be easier to understand the spaghetti Excel spreadsheet and find where it doesn't work properly !

You’ve been lucky with your spaghetti code experiences, then.

At least with spaghetti code I can set a breakpoint or add print statements and get an understanding of the execution path.