There are a number of ways to tell if you can trust a web site. Part of it is to look at the URL itself. Some people try to get you into their web site by using miss-spellings of trusted names. A difference of a letter or two and people find the wrong website. URL's that end in gov, edu or mil can normally be trusted, as the use of these suffixes are carefully controlled. You should validate the information you find on any website, even this one. It is very easy to believe anything you see in writing. All websites are genuine its the products they sell you have to worry about. Unfortunitely there really is no way of telling that the website is selling genuine products.