My MIL used to work for the BBC years ago and said some of the celebrities she heard about were totally different in real life. Bruce Forsyth was supposedly horrible and really vile to people, quite self centred and mean.
If anything, I would say that Bruce wasn't necessarily all that different in real life - in that he hid his attitude and personality in plain sight on camera. He was always very snobbish with the contestants - these 'ordinary people' who needed to win stuff when he would presumably have just bought it outright. I'll never forget one episode of The Price Is Right, when a contestant with the surname Johnson was called down and he made a point of saying that he too was a Johnson (no comment), but they were double-barrelled Forsyth-Johnsons - "because WE had money". He double-bluffed that he was joking, but it never came across as a joke or self-deprecating in the least.
He made endless causally sexist and and misogynistic remarks to female contestants (often also unnecessarily 'helping' the younger ones to reach the equipment i.e. groping them). I may be confusing him for another gameshow host here, but I'm pretty sure it was him who, when the couple won a car and the woman went to sit in the driver's seat whilst her husband headed for the passenger seat (as it happened, she drove and he didn't), Bruce went to block her way and crossly told her that she had to get in the other side.
He rarely missed an opportunity to make belittling and rude remarks about any person with a remotely 'non-white' name. I don't think he was hateful towards non-white people (otherwise he wouldn't have married his wife), but he always 'othered' them and, as I perceived it, expected them to 'know their place'.
Plenty of gameshow hosts use a bit of gentle banter with the contestants - Joe Pasquale did when he did TPIR - but it's almost always good-natured, goes both ways and done with a twinkle in their eye. Apart from the odious Barrymore, that is.