The following is a list of things to look for in online auctions:
#1) Is this an individual seller (risky) or a reputable auction house/service (much less risky) but usually has a 20% buyer Premium.
* Example - Live Auctioneers is a reputable service, you have to sign up for FREE and give them your contact info and if you are bidding, you must secure your bid with a credit card or PayPal. By joining Live Auctioneers you have access to viewing all paintings sold by any particular artist on that service (really nice benefit). They will charge a 20% buyer Premium (not a benefit).
#2) Is contact info and location of the work listed? Does somebody respond to my email or call. Does the seller have an Ebay rating, what is the shipping policy and what is the return policy?
For example, often there is a Rockmore up for auction on Ebay that we will not bid on - although it is priced fair and uses PayPal it is out of our comfort zone (no rating, return policy, has a reserve). The litmus test is how the seller responds if you say, "I want to pick it up in person." Scammers won't respond at all to this question, most legit Ebayers will be reluctant but at least they will respond.
#3) How accurate is the description and have they embellished or issued a disclaimer. Do they accept PayPal (Good) or do they want a Western Union or money order (bad - don't do it - ever).
#4) Who arranges shipping and how much is it, insured! We once won a Gladys Rockmore Davis painting for $100 from an auction house in Dallas. The best we could find for shipping in the area was $650 ($150 pick up fee). We had our daughter in Austin pick it up and paid her a nice tip on saving us $650.
#5) Beware of a Reserve Not met notice. If somebody list an item for $100 with a reserve, they can set the reserve at $10,000 or whatever they like. You don't get to know what it is if you bid, just whether or not you have met it or not. They might be trying to feel you out or test the market.
#6) Never, ever, ever respond to a "You have a second chance auction notice." The scam is that the original bidder could not pay and it is being offered to you at your high bid, it is very tempting and it is a scam on two counts. #1 - the auctioneer might have been goosing up your bid with a dummy bidder (like bridge but illegal and immoral). #2 - The emailer has no relation to the original auctioneer and simply swooped in after watching the auction with a fake Ebay message to your email (easy to do) and are hoping you are foolish enough to fall for it.
#7) Never, ever, ever enter your Ebay, Bank, CC or Auction Info because it is requested for some reason after you know you have signed on to your account. Someone has put up a fake sign in the message again. Sign off your account and then sign on again by your usual way, avoid the fake screen scam.