I'll 'fess up to one incident I caused.

I deboarded in SAS and grabbed my black Kirkland Signature (Costco) rollaboard bag--one I don't commonly see others having during my travels, even though it's a great and fairly-priced bag--from the downstairs rack. I hailed my Uber, hopped in it, and arrived at Hertz at the SAT airport (I'd booked at the fake Hertz "Amtrak station" location, which included a promise that they'd reimburse my cab fare). Just as my Uber driver was turning onto the street that Hertz was on, I got a phone call from the Amtrak conductor saying that they had my bag...and I had someone else's bag.

Sure enough, he was right. I grabbed my car and rushed back to the station to switch bags. Fortunately, the train lays over at SAS for awhile, and it actually turns out the other guy was deboarding in SAS, too, and he wasn't in a rush (and it worked out well for him as I was able to give him a lift over to the Greyhound station and save him a cab fare or a long walk). Still, the moral of the story is to always make sure that you have the correct bag when getting off...and always make sure your bag has some prominently unique distinguishing characteristics or tags or something on it so others won't mistake yours for theirs and take it off in the middle of the night.