I have had a few but I will start with the 2006 draft class.
I couldn't afford Reggie, Vince, or Leinart but I was 100% sure that Lendale White was going to be a great power back.
I dumped money into my 100%~ guarantee but it didn't work out so well for me.
Who was a bust for you?
Brian Robiskie 2009 Browns.
Had around a 50 card PC with some nice stuff before I quickly regretted these purchases.
Mardy Gilyard, Arrelious Benn...
1991, Ricky Ervins. Traded my stadium club Favre and a fleer Emmit Smith for the Pinnacle and Stadium Club Ervins RCs. At the time, Favre was worth about $1.75.
Oh, and how could I forget Lawrence Phillips! And he had some awesome cards...
Kyle Boller. I'd rather not talk about it beyond that. :p
Oh man, great topic!
For starters ALL... and I mean ALL modern RBs are bad investments. Fred Taylor was for sure my biggest wash out financially. I STILL have some serious Freddy cards including a SGC 98 Sp Authentic RC. SPx Finite BGS 9, you name it I have or had it. "Fragile Freddy" was a hard earned nickname. I still remember a mind boggling jump cut at 100 MPH and Freddy going down like he was shot by a sniper... followed directly by my "NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!"
I'll follow up by one reverse bust, Tom Brady. My hatred of Brady (too many reasons to list) started directly in 2000. While I hated the fact that Bledsoe killed the Phins repeatedly, I respected his toughness (He beat the phins on a 4th qtr. comeback TD drive with a finger pointing sideways)... Brady is like a sissy girl in comparison. I was on a mission to rid myself of EVERYTHING Brady in 2000... I thought "My god, these people are NUTS to pay $35 for an SPx rookie of this clown"... I sold 5 of them... WHOOPS :<
Larry Johnson. He cards were through the roof his first couple of years and he was on pace to be an awesome NFL back. His yards per carry, had he played the whole season (didn't because he came in after Holmes was hurt) would have shattered the 2000 yard mark.
I overpaid for one of his autos and now, while still more expensive than they should be, can be bought for next to nothing.
I recently got a graded 10 Ultimate Collection auto for 9 bucks. Back around 2005 they were going for over 200 I think and I ended up paying like 70 for his Power Picks autograph.
When the Saints drafted Sean Canfield in 2010 I figured he'd be the heir apparent to Brees and if nothing else, he'd take off with another team and I'd have trade bait. I purchased large amounts of his autographs, and nothing...