Traffic buying can be a negative factor for your website. Many traffic providers often provide low quality traffic though you pay them money. Though traffic purchasing through advertisement and other mediums can be easier ways to drive traffic towards one’s website, it can be risky to draw audience without having much knowledge about the perfect mediums of traffic-buying.

It can extend another sandbox factor for your website. When Google robot crawls your site the next time, it will not find the purchased temporary link and may not prefer new link. Older links are always better than new links.

Changing the meaning of queries frequently due to current events can be a negative factor for your site’s ranking.

To have indexing, your website must have at least one incoming link to your site. Having zero links can be a great negative factor for your website.

Getting many numbers of links in a short time span can be possible with link buying. But it can be risky because if you are caught, the penalty can be higher.

The previous ranking can add to the current ranking. The higher it is, the better it is.

Cloaking is definitely refused by Google. The Search Engine promises to ban the practices of presenting one webpage to the crawler and a different webpage to the users.

When a site receives incoming links from bad sites, it may not hurt the site-ranking. But it can hurt if the link is detected to form a web ring.

It is a kind of theft and can anytime result in imprisonment. This criminal activity can bring all your activity to standstill.

You have to follow many of the TOS of Google. Otherwise that can block your website. One of such TOS is that Google will punish you when you over-do many of the SEO techniques. For instance, near about 100 queries per day for a keyword, can make Google block your IP.

An unreliable server can drop your website from the listing. If you are not present due to some of the maintenance reason, your website will not be crawled.

Google is cleaning many computer generated pages and it is really dumping large number of pages.

Content theft from competitors’ site can cause you a great penalty. Site-side link attack can be a negative factor for your SEO. There are many other factors like 302 direct attack and hijacker attack which can come out as negative factor for your SEO and bring you penalty.

A changing algorithm can be taken as something negative factor for SEO. Those websites with high PR that stands more than 7 can sustain with the changing algorithm.  

You need to be alert about the algorithm change. It can drop or boost your site. You have to change accordingly otherwise you can be out of the game! You have to learn all the On-page techniques to get crawled and ranked by the Search Engine Crawlers.

Link acquired too quickly through many unnatural ways can penalize your site. Higher link velocity earned through unnatural means is a negative SEO off-page factor because link velocities can be increased through off-page techniques only.

Link Schemes are used to manipulate page ranking. And Google is watchful about different link schemes. You can be penalised for getting into any kind of link scheme.

The reputation of the author can have positive or negative impact on the ranking of the website. Reputation as a spammer or an anarchist can mar your whole effort to raise the ranking of your website.

Making negative comments on Google on webmaster forums can bring a negative impact for you. Personal comments must be avoided and must not be expressed in any forums.

Google Webmaster Forums have connections with Google. Posting something negative about Google can be a negative factor for your SEO.

No honesty is required for expressing anything about Search Engines. It can lead to demotion.

Apart from many known factors of SEO, it is believed there are many unknown negative factors for the demotion of your site. Any kind of personal competition or rivalry with any Google employee can too lead to low ranking of your site. YOU NEVER KNOW!

The frequent changes in the algorithm often lead to many unlisted factors of SEO that a webmaster may never know.