Not necessarily...
If they come in the triangular case with the capsule full of tips, then they are likely genuine.
However, they are also likely refurbished.
From what i have gathered, you can tell a refurbished one from a brand new one, from whether it has mesh caps or not. In both cases of refurbished AND new, retail packaging may or may not be included.
it looks like the average ebay price for refurbished models (meshcap-less) is about $35 today, though 3 weeks ago it was at $55, with a small number. comes and goes.
I bought mine on ebay, and it was new. (had mesh caps), and according to the seller, it was a leftover from a gift basket at a corporate meeting.
It is also genuine, as my dad has a apple-store bought one, to which i compared mine to. The difference was nominal, probably because at the time min had about 10 minutes on it, versus my dad's had hundreds of hours.