Hi, Most CPM and PPC networks all offer code to place on your site that is not valid xhtml 1.0 code. Placing that code on your site instantly makes your pages invalid markup... Is there anyway around this or should one not care about w3c validation?
W3C Validation doesn't really do anything. I've had sites that rank on google pg1 for keywords with 50,000+ daily searches that have had hundreds of "Errors" on W3C validator.
Validation is more or less for designers and developers to use while the site/page is being made. You really don't need to worry about it. Some ad code can be modified so that it's valid without breaking it though.