Just to share my experience;
I got a 17-55 nikon f2.8 recently from the same shop, it's my second piece. The saleman try to sell off the len that doesn't look too new. Once we agree on the price he just shown the len briefly to me before starting to pack into paper bag and ask me to pay. I told him I need to inspect the len, and guess what, the condition doesn't seem new. There's a big dust particle in the len element itself & when I told him, he said it's quite common & nothing wrong with it. The contacts also seem a bit worn off. I got a feeling he's trying to clear off those to tourist like me. (I am a full time photographer, so I guess I can trust my own judgement)
Anyway he act blur & show me another len in the shelve, this time told me this is the last piece they have. Turn out to be another len full of dust in the front element glass & a few stratch mark on the len's contact. I decide not to buy & he quickly told be he will check his store if anymore stock. This time he brought out a len that perfectly ok. How can a len that cost almost $2000 be full of dust ??
So when you are buying from oversea, do yourself a favor to check the len clearly to avoid getting cheated.