Although they look good and can sometimes act as a platform to show off, web content pages with AJAX elements
are difficult for most crawlers and scrapers to mitigate. This hurts where it matters the most on the Web: Search Engine Optimization (SEO). The problem with AJAX pages is its dynamics
, pages remain hidden to crawlers. Regular maintenance is too laborious since it entails manual updating of content.
A great example is Twitter: if you check the source, there are no tweets visible. Just lines and lines of code staring at you making everything you see dynamic! This is where AJAX crawling works.
However, potentially new crawling techniques now help search engines to crawl and index such sites / pages.