For speakers, I'd be more inclined towards Craigslist or local listings.
That is a good point!
Most people I have dealt with were honest and even exaggerated any blemishes so I was pleasantly surprised when I received them, but the opportunity to hear in person before buying eliminates a lot of risk (such as a blown tweeter, etc).
Also, shipping damage is a big concern!
If you are shipped two towers and one gets destroyed in shipping, you are stuck with a single speaker and the shipper (UPS, FedEx) will pay you 50% of what you paid for the pair. So now you have a single speaker, which is kind of worthless without it's mate. If the speaker is discontinued, you may not find a match!
Also consider the packaging. If they are SVS or Ascend speakers, the packaging should be designed for the rigors of UPS/FedEx. If something like Polk, Klipsch, or JBL, there is a good chance the packaging was designed with the idea it would be unitized/shrink-wrapped to a pallet, handled by forklift, and shipped out to distributors like BestBuy or Frys, not thrown around and dropped off the back of the truck by the UPS guy!
I am pretty comfortable having bookshelf speakers shipped, but not towers!