I posted a while back how using Wordpress themes could hurt your SEO efforts. I was working with a client in a business with very limited competition in regards to web presence. The site I built for them was far superior than any of the competition, but it wasn't ranking organically. I couldn't figure out why (which led me to research Wordpress and SEO).
I finally said fuck it, and rebuilt the entire site using Bootstrap framework. Now they're ranked #1 in all the SERPS! Eight months using Wordpress, organic rankings sucked dick. One month with no Wordpress and now it's ranked #1 for multiple keywords.
So FUCK WORDPRESS! 