Probably, if they were not standing right there or nearby or conveniently contactable when the items were discovered... but I'm not sure what you think that says. There is something called "personal responsibility" which should include collecting one's personal items before selling a camera or car or house or boat or motorhome or mountain cabin...
It says you don't care about other people much. And YOUR personal responsibility when finding something that someone accidentally left behind is to return it. Because we all fuck up. We all forget things. We all accidentally leave things behind in different places we go and we ALL would hope that someone would be nice enough to return them.
And when you don't, it says something about you.
I couldn't think of anything witty to say so I left this blank.