Before I upgraded to a MH, we used to take a 20' TT into bear country in the sierras. We would hear them occasionally at night going through the campsites looking for easy pickings. I never had them try and break into our TT. Campers that had trash cans or bags with trash left out found the contents scattered all around the campsite. I always pack bear spray and a weapon, but have never had to use either. As everyone else has mentioned, keeping your site clean is the ticket to a joyful non-event experience.