This word can also pertain to people who are tolerable for short periods of time but become annoying and even repulsive if you have to spend an extended period of time with them. You say "hi" or smile as you pass them, but when they stop you to talk they become instantly cloying.
I smiled at the hot chick in the office and she stopped to talk to me, after 5 minutes of her rambling on, she became cloying and now I avoid her.
Some of the most cloying celebrities are: Gilbert Goddfried, Jim Carey, Donald Trump, Kanye West, Chris Brown and Jessica Simpson. I can take them at first, but after a few minutes I have to change the channel.