We camped at a NFS campground in Colorado (Lake Irwin) a few years back. A bear was in the campground at dusk. He found some food left on a table and created quite a mess. He then opened the upper window of a truck camper and helped himself to a package of Oreos.
About 2-3 hours later we were drifting off to sleep in our class B van and we felt a big push against the side of the unit. Kind of freaked us out. We stayed inside. In the morning we looked at our campsite and the only thing amiss was the huge tears in our vinyl tablecloth on the picnic table. Can you say "Bear Claw?"
So just be sure to pack your food items away from any windows and maybe inside some boxes.