As you stated yourself, a code is only as sloppy (or as clean) as you ... code it. It has nothing to do with a system.
I'm not sure how you handwrite code in Wordpad though. For hand-coding HTML, you need a plain text editor, which Wordpad is not.
And HTML has a strict DTD too, not just XHTML.
Finally, you should use XHTML only if you really use it, not as a catching net for coding errors. That's wrong. And strange. And it has the reverse effect on the browser, since you obviously won't be serving it as application/xhtml+xml or application/xml.