I've had one bear incident, camping in the general area of the old Wilderness Trail Bridge past Bondcliff. The bear in question was named Brutus, was well-known by rangers...and was quite large for a black bear.
Turns out, there were three separate camps set within a mile of each other. One site, up the Thoreau Falls trails, had a man and his son who had their hanging food ripped out and stolen overnight. They never heard it at all, but saw the remnants.
Soon after it appears, he made his way to our camp. Now, in this case, we were 100% to blame. The 3rd night of a long trip in the woods, we got too lazy to clean up our camp. I was up early with my dog, while the other 5 campers slept in their tents. Brutus appeared out of nowhere, and wanted our pot of Spanish rice. The commotion of the dog barking and me yelling at him didn't scare him off, but when the rest of the campers woke up and he finally realized he was outnumbered 6-1 and not worth the hassle, so he scooted downstream.
About 30 minutes later, a solo hiker appeared in bare feet, carrying his boots and his pack. Seems Brutus came up from behind and stole whatever he was eating. He grabbed his stuff (he was already virtually packed) and got out of there. The man and his son appeared soon after and told us their tale.
When we got back to Lincoln Woods, we talked to the rangers and their comments were along the lines of "That sounds like Brutus. It may be time to put him down...". I believe he was eventually removed/relocated/put down. From stories I've heard, he had a good circuit of areas he would hit nightly and caused a lot of problems in the Desolation area, especially.
I've seen lots of fresh scat and my dog had her nose up on many occasions, but other than one running away well ahead of us, that was the only time in the Whites (see them more often around my house in Southern, NH).