... Well check for the logos on all sides and areas of the products. They should feel nice and the cushions for the ear cups very squishy. They should also be padded at the top and have a red coord.
Here is some advice from the official beats be ware section kind of thing:
HERE ARE A FEW TIPS ON HOW TO SPOT FAKES:
If the price seems too good to be true, it probably is. Genuine Beats products are made with premium materials and are designed to deliver a one-of-a-kind listening experience.
If a website is offering low pricing if you buy more than one pair, they’re not an authorized Beats by Dr. Dre dealer.
Make sure the shrink-wrap on the exterior is tight and professional. Auction sites offering products with no box or manual, no warranty or documentation, are counterfeit. Bottom line: if you get Beats products in unprofessional packaging, they’re fake.
Any cheap, faded, damaged packaging, labeling, strange markings or misspelled words are all sure signs of counterfeits.
Source:
http://www.beatsbydre.com/support/buying/safe-buying-guide.html