Compliance with W3C HTML standard is it a ranking factor?

If I make the effort of modifying the code of my pages to make the source code fully compliant with the W3C HTML standard, and they pass the validation test, will it gives a better ranking to my site ? Does Google favor compliant sites?

HTML compliance

In fact, nobody ever said that a page should be coded in HTML to be indexed by search engines, the most notable of them at least.
Hence why a page which does conform to this standard should therefore be better ranked?

Plain text pages are indexed as well as HTML pages, that can be verified by placing a unique content in a text file and include it in the site map.

On the other hand, it is certain that if a page is a mixture of text and tags so that it is impossible to recognize each from other, this will not help to index the useful content.
Google implements a parser that works like a browser displaying only the basic textual content. We can check pages with a such tool is to know how crawlers see them.

HTML Optimization

Using HTML (or XHTML) is preferable for better indexing because it contains some tag crucial for ranking:

If these tags are missing, or if they are not well-formed and not recognized this is detrimental to ranking.

In conclusion, a strict compliance to standard is not essential, while the content can be correctly interpreted.