Absolutely! I personally have always advocated such a "look" test:
http://adtmag.com/articles/2004/03/01/keep-your-xml-clean.aspx
"The next time you develop an XML design, print out a sample document
and hold it up to a colleague for a quick read. If he or she develops a
headache from trying to figure out what it means, consider this an omen
of the pain that maintaining the format will cause in the future."
Not too many of us can avoid a headache from a 50MB pile of raw data, and angle brackets do nothing to help.