If you see Swarovski spotting or rifle scopes at an unrealistic price, it's likely a scam.  Typically, these listings will have an e-mail address listed and instructions to contact the seller before bidding for more information.  In most cases, the bidders will be kept private (so nobody can contact prospective buyers to warn them), the auctions will be only one-day, and often the item will be listed in an inapproprate category (to make them harder to find by ebay admins).  A sure sign is if you see a variety of other unrelated popular expensive items also offerred by the same seller when you check their other listings.  Since they don't really have any of these items, they don't care what it is, they just pick things that they know will attract attention and will generate the most money.  

If you do contact the e-mail address, you'll receive an automated reply with instructions on how to send payment via Western Union (or other methods).  DO NOT SEND ANY MONEY VIA ANY MEANS.  These are all scams and you'll receive nothing.  They want you to use Western Union because they can accept payments anonymously and there's no recourse for recovery as a buyer.

If you see these listings, then you can contact ebay's Safe Harbor group here:  Report a Fraudulent Listing here

Most are using hacked accounts, but it may also be helpful to send a note to the seller so that the real seller will be aware that their account has been compromised.