Comment I validate... Kinda (Score 1) 624
I design and code my sites in Visual Studio; though the ASP.NET C# code generates additional HTML that can't be checked from within VS2005. I try to keep that part as close to W3C as possible, but sometimes compliance just makes it harder to get things done. The CSS validates, usually...
The biggest problem I see is alot of web hosts add non-compliant tracking code to each page.