Currently, I generally don't either. I do have an exception though...if I find a journal, I take it. Journals are a part of history, and once they're gone, they're gone. At least if they come with me, then they'll be pretty safe.
One of the houses I took a journal from (a gardening journal from 1952...not too interesting...) has been renovated since, and I've been debating anonymously sending it to the owners lol. The other journal I found was a desk journal from 1958...but sadly we discovered it was empty.
Sometimes things are too gross though, so a picture is just fine. Another place I found a newspaper from 1939, but it had been left to the weather and so I took a picture and left it with the house.
When I first started, I took a whole bunch of shit. Not to say I'm proud of it or anything, but we stole two extension cords, two fire extinguishers, prices of a lighting fixture and curtains from a house in the abandoned neighborhood at Norwich State. But that was 8 years ago, so could I still get in trouble for it? Probably... lol Another house, we stole a book on Legendary Connecticut, and while looking at it a little while later, discovered that it was signed by the author. Shit.