Looking like I'm late on this thread...
I had discussed the issues and how to improve the Sales Section Earlier in this thread...
Without pointing towards any specific posts, I have noticed, more often than not, listings in the "For Sale" section include a reference/comparison price which is a recently quoted price by some local (to the seller) dealer or some random number (eg. "This item currently goes for 2L") without...
www.hifivision.com
@op I'm using a Cxn v2 Streamer and I have never used the WiFi, In fact I have never used the AVR Wi-Fi as well. When you are serious about audiophile SQ (as indicated by buying the Streamer) you should look for upgrading to wired Etherenet connection.
Having said that, if you had specifically asked for wifi dongle status, it's totally misrepresentation by the seller, otherwise it becomes a difficult proposition. Ideally yes, Seller should have mentioned that he hasn't checked WiFi dongle, but it is unpredictable.
Also ask for a invoice whenever someone says he's the first buyer, or any proof of transaction, a CC bill maybe ; if he's unable to produce one, you're free to bargain and take a call. In spite of everything, it's mostly a leap of faith and buying Pre-owned always comes with its own set of risks.