Any time you buy designer clothing at a place other than an authentic retailer, you run the risk of buying a fake. Some fakes are so badly done there is no question as to their authenticity, but sometimes they are actually quite close to the original and it can be difficult to tell.
Ask yourself some questions before you start. How cheap is it? If it's very cheap and it's not used, be suspicious. Who are you buying from? A department store is usually fairly safe but street markets are a big gamble. Are you traveling in Asia where there is an overabundance of fake items? Are you buying from eBay? If so, make sure the seller has a high rating over a long period of time. eBay has a lot of reputable sellers who make their living this way, but there are also a lot of people selling fakes.
Look carefully. Some fakes are so bad you can tell without close investigation. Check to see if sleeves are even and if there are any obvious defects like holes. Look for any signs of bad stitching or sloppy work. Ralph Lauren does not do sloppy work.
Touch the fabric. Bad fakes will feel hard and stiff. Ralph Lauren polos are soft and made of 100 percent cotton.
Look at the label. Make sure everything is spelled correctly! Real Ralph Lauren tags say Polo (in a box) by Ralph Lauren and have threads on the back; fake tags often do not have the threads. Real Ralph Lauren polos have a separate smaller tag beneath the main tag that says "custom fit." Fakes might not have the tag, or they might put it on the side. Real Ralph Lauren polos have a third small tag on the right side of the main label with the size and "100% cotton" on it. This tag is turned sideways. Fakes often have the tag with the size under the main label.
Look at the stitching. Real Ralph Lauren polos are stitched together perfectly straight with matching thread. The stitching on the shoulders of fakes sometimes look just like two pieces of fabric stitched together rather than a piece that has been folded over and stitched.
Look at the underside of the horse. It should be neatly stitched on. If there is a bunch of white material sticking out under the horse or if the stitching is not neat, then it's a fake.