Depends on the beats model, but all of them have this cleaning cloth, it shouldn't be folded, but the plastic where its in should be folded. That works for every model to see if they're real. Of course, some fakes do have this, so you need to dig deeper.
With a beats pro/beats pro detox for example, the carrying pouch has a metal cliplike thingy on it, with the fake's this is plastic.
A real beats pro/pro detox has this cable with a coil, and the coil to the 3.5mm L-jack is exactly 7 centimeters. With fakes this ranges from 15 cm up to about 40 cm.
Here are way, way more ways to see it, they're really bad at faking beats, especially the pro and detox.
Edit: The most common way to see if a Solo HD is fake, is look at the plug that goes inside the headphone, a lot of fakes (not all, but a lot of them) are plain red, but the jack should be black, with a ring of red and a ring of white, with the text "monster" or "beats" on it.
Edited by kilspeed111 - 4/10/14 at 5:14am