Really look at the details
When it comes down to trademarks it is really important to look at the details. I found out just how much detail recently on a submission where a patent number, barely visible but still there, held things up.
I never noticed it until I really got zoomed in on the image and there it was. little things like this will make or break a stock image. Two solutions are available for this problem.
If it's a generic enough item in the photo then remove any identifying symbols, logo's, numbers, letters, or anything at all that can be linked to an identification. If this can't be done or the object is a recognizable piece, building, monument, artwork, or anything you can say, "that's a (place name brand here)" then you'll need to get a property release signed.
Honestly this is an extremely important legal step that must be done. If you miss the detail you can bet the reviewing editor won't and the image will be rejected. Take the time to check, recheck, walk away and then check a third time. In the long run it is better for you and DT.
Photo credits: Mark Birks.