I got burned 3 times - I'm a slow learner.  All auctions were for lots of coins worth a certain amount - e.g. $8000, $10500, and $2800+++.  None of the auctions listed the coins you would receive, just that they were certified and worth the value listed in the title.  All were mostly junk sets.  Perhaps the sellers wait until you win the auction, then say 'well he won my $8000 for $500, so I'll send him $200 worth of coins.'  I guess it was silly of me to think a seller would part with $8000 or more of coins for less than $7500 or so.  One issue is that all 3 of them included little price guides with highly inflated values - nothing a dealer or reputable price guy would give - some were over 100 times more than any guide or ebay store buy-it-now price would be.  The other big problem was that most coins were graded by unreliable graders. E.g. listing
INVESTMENT LOT PCGS, NGC, ICG
$10,500.00 NO RESERVE!!
This means that 1 coin will be PCGS or NGC, the rest will be ICG.  Never heard of them?  There is a reason.  ANI is another fake grader.  Only PCGS and NGC guarantee the coins - if you receive a coin slabbed as MS67 and later it is graded as MS65, PCGS will trade you a MS67 for it, or give you the money difference.  ANI, ICG and others are just for profit slabbers who make dealers happy by over grading everything.  A highly smudged and scratched quarter (circulated condition), was slabbed by ICG as MS70 - there is no way that is a correct grade if the naked eye can see belemishs. 

I learned the hard way that there is no free lunch, if the seller does not list exact coins, and they are graded by PCGS or NGC then you will be ripped off.  They quickly refund if you figure them out so they keep high feedback.  But I am sure lots of people a) fall for the inflated price guides included without checking a recognized price guide or local dealer appraisal, b) do not get an appraisal and do not have the experience to recognize the over grading where an AU55 coins is listed as MS70. 

I am disputing all 3 mistakes I made, please don't fall for this too.  I just want my bid money back, so I'm not stuck with a bunch of recent quarters and dimes that have been slabbed and rated at $40,000 when they are worth maybe $200 as change.  Again, why would us buyers honestly believe a seller would send $28,000 value of coins to someone for only a bid of $500-$600.  If they were worth anything close to $28,000, they would sell them for that, right?

I asked the $10,500 to buy them back for $10,000, a profit of $500 for him.  He laughed at that, which I claimed demonstrates that he knows the lot is almost worthless.  So I will  my $300 bid back.  And he will relist this investment lot, no reserve, and someone will buy it and think all slabbed coins are the same.  Wait until the buyer tries to sell his $12,000 penny.  I got one, it is probably worth 1 cent - a highly used coin, way over graded, and even if graded correctly would be $180 or so, but it isn't Mint State nothing!!