Forum Moderators: phranque
The exception, I think, is dynamic programming that uses rediculously=long&query=strings&in=the&URI+or+URL. This can be remedied by careful integration with mod_rewrite so you can user keyword_rich_URIs to point to cryptic query strings.
The two bolded points above are important, though. I've seen tons of ASP pages disabled by spurious errors, and a lot of server-side programming still use font tags, invalid nesting, and other tricks to capitalize presentation over semantics. If you program from scratch, it doesn't hurt to validate yor output. :-)