There are many reasons that second chance offers are a bad idea, primarily because they are so open to fraud from either the seller or unassociated 3rd parties.
1. Sellers can bid against you running a second i.d. or via a 'friend'. this way they raise the price to themselves if the item sells and raise the price on a second chance offer if it doesn't sell. Either way, theres an excellent chance you'd be out of pocket on a second chance offer purchase.
2. E-mails that don't originate from your E-Bay e-mail offering second chance offers are from fraudsters. I have personal experience of this when I bid on a high value laptop item and was offered the second chance at the end of auction. The e-mail to my private e-mail address that looked 100% geniune E-Bay. I checked back to my E-Bay account inbox and there was no sign of the e-mail there and the laptop seller confirmed that the laptop had been dispatched to the auction winner.
E-Bay & PayPal customer service is non existant and verging on negligent so if you do end up as the victim your pretty much on your own. I contacted E-Bay & PayPal to report the high value fraud attempt, sending the HTML code, and the only thing that came back was an automated response stating the e-mail didn't originate from E-Bay so don't act upon it. I contacted the police, not interested since I never actually handed over any money but gave me a direct E-Bay e-mail address thats supposed to be personed. I sent the tale to this second E-Bay address and guess what, an automated response came back stating that the e-mail didn't originate from E-Bay. Whoopeee, like I didn't already know that.