High ad ratio- websites that constitute more ads than actual content rank quite highly within Google Panda’s target list as they will usually involve a watering down of information in favor of allowing for greater space for ads.
Page hijacking is one of the less savory targets of Google panda, referring to those sites that duplicate pages from prominent websites, whose links impel users towards malicious websites designed to elicit all manner of negative consequences.
Google Panda frowns quite deeply upon hidden text; hidden referring to various forms of obscuring the visibility of text, from using very tiny fonts to slipping it into the HTML.
Empty pages- there are several reasons that would lead a websites to possess many an empty web page; and whatever the reasoning the more empty web pages a site has, the greater the chances of attracting penalization from Google Panda.
Here is the bottom line. What is Google Panda? It is an algorithmic alteration Google designed to penalize those individuals that intend to cash in on the benefits of Search engine Optimization through a series of near illegal and usually unfair short cuts that skew the playing field.
There is an attempt on Google’s part to force a modicum of honesty into the current SEO game, this a reaction to the number of sites that have, over the years, achieved high rankings through short cuts. Google wants site owners to do their work, hard as it may be, slog through the trenches like everyone else and achieve and maintain their rankings through those most honest SEO techniques.