I do tons of KO reviews, not only for those that want them but also to be able to distinguish. My advice is to order from a reputable site. Ebay is a crapshoot as most have stated, but you always have Paypal to back you up in case you are wrongfully sold a KO. Low prices almost always mean KO. Some honest sites will also label KO as KO's and have them priced accordingly.
If you are at a show where you can see the box, most KO boxes lack the sharp edges on the boxes and have darker low contrast pictures on the box. Also most blues on the box will appear purple.
As someone said earlier, the toys are actually well done so having them loose in hand does nothing to really show off its legitimacy or lack thereof.
This is a link to my KO review playlist on youtube, hope it helps. https://www.youtube.com/playlist?list=P ... PIhhnX0OnS