Generally you could just take any luggage from the conveyer belt and may get away with it. Which allows for a much targeted approach of stealing with the intend to shame or harm somebody, an immoral act, that is illegal.

My luggage was pillaged for valuables during a longer bus trip in Thailand, the criminals took a ride along in the luggage compartment of the bus. Luckily they only got my electric toothbrush and some shaving blades. Still...

Just have everything of value in your carry on and only check in things that can get lost. The bulk of lost luggage is simply this, stuff people don't value enough for the hassle to get it back, which is a pain with airlines. I have lost luggage on conferences and lost a really cool beany and umbrella because of it, I can't get anywhere anymore. No question, it sucks especially with airlines. The process of getting something back or compensation is very annoying on purpose.

Still I wouldn't assume that I could buy illegal or incriminating material from auctions of lost luggage or that such an transaction is generally immoral.

I'm afraight that if it is possible for one to identify the owner of auctioned lost luggage, one would be obliged to contact them about it. While using this for blackmail or shaming would not only be immoral, but also illegal in most cases.

The act of selling the luggage after some effort to find the owner, is not, I think.