Mystery Boxes are becoming one of the most watched items on ebay.  They are fun and they often let sellers meet prospective buyers for their other products as well.  Ebay rules prevent sellers from revealing the real value of any additional gifts that may be included with the item you are bidding on, which may be a box, purse, envelope, etc.  This is the risk of perhaps paying more than what the contents are actually worth.  Most sellers of mystery auctions are legit and don't want bad feedback, so they will not try to "scam" you by sending you junk; however, you still should be wary of some mystery auctions.  Things to look for are mysteries promising to be thousands of dollars in cash or an extremely high amount in the cost of merchandise.  Now it is possible that you will win a mystery auction for $100 and get items that have a much higher retail value because sellers often have things to sell that they bought below cost, just like a traditional store.  It is also possible that someone may have 10 of thousands of dollars worth of merchandise, but it is not worth anything because something like electronics may be outdated.  So, you should check what the seller's other items they are also offering. 

Also, read all contents of a mystery auction.  Sometimes someone will list a designer purse, and call it something like, "The Coach Mystery Auction," but you read and discover that you are only bidding on a Coach box.  If a seller lists a Coach purse and says you are bidding on this purse and other gifts from me will be included, then you should be getting the purse and other items, but you may want to confirm that before bidding.  I recommend avoiding new sellers for mystery gifts or auctions.  While everyone needs a start, it is easy to sign-up on ebay and open a sellers account, make some money by scamming people, and then disappear in cyberspace. 

Also, read a sellers' feedback.  If a seller has good feedback, then it is likely you can trust them.  I would avoid sellers with mixed feedback and those who keep their feedback private, because I think this is a red flag for risk.  I think sellers who offer a return policy are also most likely safe as well, because they are in a way insuring that you will not be ripped off.  

As a bidder, you should bid only what you are willing to pay and be realistic in your expectations.  If you win a mystery auction and get items you do not like, unless the seller grossly misrepresented the items, then you have no reason to be sore with the seller. 

No seller can promise everyone will like all their items, but as long as they told what may be included, and made no gross misstatements, they did their job.  Also, sellers who offer a return policy often want ALL of the items returned and they want them back as they were sent, which is fair. 

I think mystery auctions can be fun and can yield some great items.  Plus, surprises are nice.  Just be careful on who you buy from and what you bid on.  Also, watch some of these auctions.  They are entertaining and sellers often offer gifts to random watchers.  The gifts could be anything but it is something for free, so no risk there.  I hope this was useful and I hope you join the mystery fun!!!