There are numerous guides on how to spot fake designer clothes.  I was unable to find the information I was looking for as to the Polo big pony shirts, so I decided to write my own guide. 

I will focus on the things that I have learned, and that I was unable to find on these eBay guides. 

I have included several pictures of two shirts which I bought right here, off of eBay.  The black one is the fake, and came from Thailand.  The white one is genuine, and came from a seller in New York with a positive reputation.

Logos

Genuine Polo big pony logos are very detailed.  The craftsmanship is very evident.  Features are crisp, and easily discerned.  From the inside, the attention to detail is the same.  The horse should look like it is galloping, not jumping.  The logo overall should feel very thick.

Fake logos do not have the same attention to detail.  There may be an uneven number of stripes on each leg of the horse.  On the inside of the shirt, there may be a backing of some sort.  The logo on fakes will not feel thick and heavy, but light and flimsy.

As you can notice, the logo on the fake shirt looks 'off.'  The size isn't proportional, the faces look distorted, and the fraud is very evident in the polo player's mallet.  The real shirt has a straight mallet, while the fake one bends behind the player's head.  Unfortunately, I don't have a fake multi-colored player to compare.

Sleeve Numbers

Polo is played by teams of 4.  Each player wears a number on their sleeve corresponding to their position.  1 is the most offensive, 2 is generally the best all-around player, 3 is the leader, and must be able to hit the ball long ways to player 1 and 2, and 4 is primarily a defensive player.  Some American polo matches add a 5th player.  Ralph Lauren puts one of these numbers on the sleeve, but the number 5 shirts are much more difficult to find.

Any shirt with a number other than 1-5 is an obvious fake.  Also, if the logo on the chest and the number are different colors, that is another dead giveaway of a fake.

Aside from the fact that the fake shirt has a number '9' on it, take note of the size.  The '4' is very prominent, and is several inches taller than the fake 9. 

Hems

All Ralph Lauren Polo hems are uneven, and vented.  The back of the shirt is generally around 2-3 inches longer than the front.  This step requires additional time in the manufacturing process, and is too time consuming for a faker to do.  Even hems are always an indicator of fraud.

Here the hems are very apparent.  Also, in the picture on the right, you can notice that on the inside of the genuine shirt is a blue gussett.  I have several real shirts, and not all of them have this feature.  All of the multicolored logos come with this, however.  Mine are either red or blue, but I have seen other colors, such as green, orange, yellow, and others.

Tags

Tags on the inside of the shirt should read in large letters, inside a box "POLO."  Underneath that it will say "By Ralph Lauren."  Any deviation on this should alert you to a fraud. 

Also, pay attention to the way the tag is sewn into the inside of the collar.  Ralph Lauren uses the same color as the shirt body to sew the tag, and only sews the ends.  For example, a genuine Ralph Lauren green shirt will have green thread used to sew the tag.  Fakers use the same color as the tag itself, navy blue.  Some fakers will even sew all four sides of the tag.

This isn't the best picture I've taken (after all, I'm a paramedic, not a photographer...), but as you can see, the wording on the fake one just "doesn't look right."  You may not be able to tell, but the thread on the genuine tag is white, while it is navy blue on the fake ones.

Other issues

Some people have made mention of the fact that genuine Ralph Lauren shirts have an extra button sewn into the seam near the bottom, on the same side as the logo.  I have found this to be the case on the majority of their long-sleeved dress shirts, but not on all of the polos.  I am not sure if this method can be used to identify a fake or not. 

The collar should be of a stiffer material than the shirt itself.  You should be able to put the collar straight up, and have it stay there.

Shirts purchased directly from a brick and mortar Ralph Lauren store do not come in poly bags.  Shirts shipped from their website do, however.  Bad grammar, such as misspelled words or inaccurate sizing charts are dead giveaways.  Ralph Lauren himself was born in the Bronx, and is well educated.  He would not misspell the words "body" and "rinse."  A faker overseas, say, in Thailand, would misspell these common words.

Genuine poly bags have the same warning in several languages.  Fake ones from overseas have some sort of a sizing chart.   And again, the writing and logos "just don't look right" on fake poly bags. 

Finally, where is your item shipping from?  Does the seller have it in stock, or is it drop shipped?  The inability of a seller to provide you with additional pictures should give you a hint that it's not for real.  Also, keep in mind that these shirts retail for $75-90 at poloralphlauren.com, as well as in their stores and mall retail stores.  A $15 big pony shirt should alert you to a possible fraud, although there are deals to be had on eBay.

I hope this guide was helpful to you.  I personally enjoy the timeless classy appeal of everything Ralph Lauren.  It dismays me that a person looking for the same timeless classic might get ripped off by a fraud on eBay.