So you've found another great bargain auction.  Exactly the thing you want - perhaps its a one-of-a-kind, a collectible.

There's one snag:  the seller is new, or has a bad record.  How can you verify the trustworthiness of the seller?

Ask a question.

Even if (especially if) you are the world's greatest expert on the product, ask the seller something.  Inquire about packaging methods, the vintage/edition/authenticity, the purpose, the history or the condition of the item.

You can gauge the professionalism, trust-worthiness, and expertise of the seller by the response.  Helpful, knowledgable, frank, and punctual replies can help you assess whether you want to do business with this person.

Also, consider how much the item will cost.  Maybe its worth giving the new guy a chance if its only a few bucks.

Sellers:  do not waste words.  You project an impression of your business with each email.  Make every exchange courteous and pleasant.  Be honest and knowledgable about your item. 

I always ask sellers questions before I bid. 

While there's still no guarantee of anything, you can learn a lot from writing to a seller.