What is Grey SEO

[davidfleming]

Gray hat SEO is a collaboration of White hat and Black hat SEO. We should only concentrate on white hat SEO. Gray hat SEO may cause a negative effect in search engine ranking.

[ashleydaniel]

It is the mid-state of white and black hat SEO.  It can be used effectively by a professional. Duplicate content creation, Buying links, cloaking, buying existing domains are some techniques of Grey hat SEO. If must be handled care. Else the site will get penalized.

[ManiQuadraIncorp]

Gray hat SEO is SEO methods that take more risks than white hat SEO strategies but aren't likely to get your site suspended from search engines (although a search engine penalty could result).

[xhuyvn]

it so hard to define what is gray hat SEO. The gray SEO is mean you SEO by black hat and use more money.
example : when use autosurf to get a lot traffic to your site. the black hat will show autosurf site on refference, gray hat just show no reffer or reffer from google, yahoo, twitter... i think this is simple define for gray hat SEO 

[TomClarke]

In the SEO, grey hat SEO  is the manipulation websites' search engine rankings using improreror unethical means but that are not considered search engine spam. This strategy is the most effective and suitable for almost all types of websites, which can bring good results without any harm.