I’m constantly surprised by the number of people who don’t quite understand how validation works. I don’t claim to be an expert, but as I understand it, you have a set of rules, and if you present something that breaks those rules, then what you have done is not valid.
People constantly posts messages to the www-validator list with the belief that their invalid HTML is somehow correct, and the validator must be wrong. (Some go so far as to suggest the validator be fixed to report their invalid markup as valid!) I can’t complain too much, because these people are most often not well versed in writing valid markup, or understanding what the DOCTYPE they chose actually allows, and they get big credit for attemping to validate their work. (May 2004 seems to have more messages than any previous month so far.)
Still, it often feels like someone keeps telling you 2 + 2 = 5, and every time you explain that it’s a simple matter that 2 + 2 = 4, another person comes along to tell you 2 + 2 = 5.
While it’s true that the W3C MarkUp Validator has it’s limitations (as most validators probably do) chances are it knows HTML better than most people do…
(And please, for the love of all that is good, tell everyone you know how to encode & into & within HTML!)