Having a high search engine ranking isn't an objective all by itself. The objective is that people looking on specific keywords would go to your site and not your competition. It is a race for eyeballs and clicks.

The best moral route for doing as such is to have interesting and relevant content for your visitors.

I have mentioned some points about how people are abusing SEO:

• Search Engine Spamming: Abuse by some starts to occur with any new and emerging technology, and that does limit usefulness, just like Spam for email.
• The WordPress Debacle: Misuse of WordPress
• The Syndic8 Debacle: Website that uses lots of links and useless keywords in articles was prohibited by Google, and had its Ad sense account suspended.
• High Paying Keywords: Some sites even target high paying Ad Words keywords, which provide more dollars per click than other keywords.
• Blogging and Ads: Abusing by some bloggers that have turned into a blog enterpreneurs
• Flooding the Ads: Another annoying practice is flooding Google Ads by a few sites.