If you have a business website, you most likely receive lots of SEO companies that promise to make your website more SEO compliant. Some of these companies claim to know secrets to greatly improve your SEO rankings. What they may fail to tell you is that some of their techniques can have the opposite effect. Those end up getting you banned from many search engines!
Whenever an SEO company meets with you, ask to see an example of their work. Check that site out yourself. For instance, does it get lots of internet traffic? A quick check of Quantcast can allow you to check and compare that site traffic to your own. If the website traffic seems low (or lower than your own website), look at the page they gave to you as an example and look for some of these "tricks"!