I've known this simply because of the "second chance" offers I have received right after the auction closes. I have a policy of never accepting them. What I do is to shop ebay to see what something is going for; the realistic and reasonable price and then I wait until the last hour or minutes and put in my maximum bid. That way the "snipers" can't get me in the last few seconds. I have a timer by my computer to remind me when to place the bid. Works well and I have gotten some very good deals. And always check the reputation of the sellers and read the comments. And I'll give another clue as to getting the best price. Check the model # of various items and see if a cross referenced part is selling for less money. I purchased an identical cordless phone battery for a camera that was exactly the same and had a buy it now price $2 less than the cordless phone battery by the same seller. Guess which one I bought; actually two so I would have a spare. Working just fine in my phone. Got it yesterday. The thing that get my goat most of all are these crooks with their outrageous shipping costs. I give them the one finger salute and I understand that ebay if finally cracking down on that racket. Having said all this I use ebay frequently and have yet to be ripped off and maintain a 100% reputation that I value and treasure.
Most "second chance offers" are bogus. One of eBay's biggest screwups was starting this feature. Many sellers are now running private auctions simply to thwart the scammers who send out fake second chance offers.
Obviously, it seems to me, there are bots running against certain types of eBay auctions sending out phishing (fake) "Second Chance Offers". I suspect that is what you are getting.