Yes. I had a job at Walt Disney World in Conventions and Special Events, where, for awhile, I was able to meet many many celebrities. There are three that come to mind as "biggest jerks of all time." They are:
1. Willard Scott (formerly of the Today Show). He has a fake charm and niceness that he turns on when he's in front of the camera or when it benefits him to be nice, but he's pretty much a complete jerk when he's off stage or off camera. His language was full of swear words and his attitude was that he was better than everyone else. Pretty uppity for a guy who got his start playing Ronald McDonald in old McDonald's commercials.
2. Kathy Lee Gifford (former hostess of Live with Regis and Kathy Lee). She is a WHINER big time, and she's very spoiled. Everything has to be Just So to suit her, and the minute things aren't going 100% her way, she starts to whine and complain.
3. Bryant Gumbel (coincidentally, also formerly of the Today show). This man has the biggest chip on his shoulder that I've ever seen in my life about being black. He takes himself WAY too seriously, and when I was assigned to him at Walt Disney World, he refused to work with me, asking my managers to "please send someone that's black."
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EDIT: Smiley, I also met James "Scotty" Doohan. I had him on board my sub when I worked at 20,000 Leagues Under the Sea at Walt Disney World. He reveled in the celebrity-ness that he had as Scotty, and at the conclusion of the ride, I gave him the microphone and he says something like "Captain, I don't know how much more of this the ship can take. She'll blow apart for sure!" and got a standing ovation from all on board. He will be missed for sure.