Matt Confirmed that almost all the penalties caused due to violation of Google quality guidelines, rather any bugs, or tech related issues in website.
One user Steve Plunkett asked on twitter to Matt confirming percentage of penalties in terms of quality, tech issues or bugs
@mattcutts question.. what percentage of penalties/filters in are based on violations of GWT quality guidelines, tech? content?? =) chart?
— steveplunkett (@steveplunkett) March 26, 2014
Answering this Matt said that almost all penalties are for quality guidelines. While if someone violate of tech guidelines, they prune those pages, here is what Matt said
@steveplunkett almost all for quality violations. Violations of tech guidelines typically just result in those pages being pruned.
— Matt Cutts (@mattcutts) March 27, 2014
So be aware to take care of Google Webmaster quality guidelines before applying SEO for your website.
