it's all up for speculation...but I think it could include: 1) too many backlinks at once for a brand new site 2) same as #1, but having too many of them with the same anchor text 3) having mostly duplicate content or RSS pulls 4) using a previously owned domain that has been penalized
if you have a new doamain then don't try to make huge backlins in begning , plz wait for 2 to 3 months and them you can do huge linkbuilding for your site and other methods for seo
Only one real reason, all the others are factors, not reasons. If there are adwords next to the search term/ keywords then the term will sandbox Thus if the G bot thinks some muppet will pay $5.00 then the sandbox algo gets tripped and BANG your new site gets wasted for 10 months, whilst the 8 year old site that was updated on Boxing day by Mrs Sloper from Basingstoke to show pictures of her grandchildren will rocket past you in the serps. There are many things in life that masquerade. We have newspapers that people buy to read the news whilst it clearly is not, We have search engines that are designed to give the most relevant results, but clearly do not. G is a business plan as much as a search engine. The sandbox is 20%??? of Googles profit