How does badly formatted HTML affect SEO?

[OptiBacUK]

Our website uses a custom built CMS, but uses a fairly standard WYSIWYG text editor.

I've looked at some of the code it produces, and it's not pretty. My gut feeling tells me that this extra bloat is bad for SEO.

Am I right in thinking that Google doesn't look kindly upon badly formatted and bloated HTML?

Thanks,
James

[OptiBacUK]

Great, thanks for the info. I always thought Google was really hot on compliance, but good to know there is a bit of leeway.

[NakulGoyal]

James, You might also want to look at the cached version of your page and then click on Text-only version and see if it shows up correctly. If it does, no need to worry from that perspective, but definitely worth checking from a usability, accessibility etc.

[CMC-SD]

The main concern is whether or not the spider can read the HTML. If something's broken, the spider may get confused. It's a good idea to check the site's W3C compliance and correct what you can, but I'm certain the search engines don't ding you if you're not perfectly compliant.

The real problems with bad HTML are load times and cross-browser compatibility. (Although, frankly, great HTML can have cross-browser compatibility issues, since IE still refuses to get with the program.) Make sure the site looks good in all major browsers.

[Matt-Williamson]

As long as the code produced is readable in a web browser then it being bloated shouldn't have much of an impact in terms of SEO. The code bloats only downside is that it might slow the page load which will have impact on SEO. Remember crawlers like Google bot essentially look at the page content in terms of textual content, what labels (alt tags etc), images and links are on there not how neatly it is presented or whether it is valid markup or not. I would take a look at your page speed otherwise I would worry as long as it is able to fulfil all the basic on page requirements such as headers, page titles etc.

Just to reiterate this - I have worked with CMS driven sites that aren't W3C compliant and don't produce the nicest html, but have loaded fast and ranked in the top 3 for competitive terms.