I never had a bad experience,Just a funny one. when I was at LTT for dinner one night while on my honeymoon, Minnie Mouse while posing with DH for a picture ,did Pass Gas really, really loudly and made us crack up laughing.She made gestures like she was so embarassed.
While this is EXTREMELY funny

...Poor Minnie! Maybe she didn't feel very well. Major bummer for her.
I try to stay pretty positive and not give any of the CM's a hard time because I don't know what kind of things they have to deal with, but I do have one moment that to this day confuses me.
We were at AK and went to Camp Minnie-Mickey during FoTLK. Needless to say, the place was completely deserted. Maybe three other families were around meeting characters. Well we met Mickey, Goofy and Donald and had great interactions and great photo ops. Well we go up to meet Minnie, and there was one family in front of us. After that family, Minnie went to take a break. We decided to stick around because we needed the break and the handler said she'd be back in 10 minutes.
SO....the place is completely empty, a fresh "new" Minnie comes out, and so my friend goes up to meet her. She asks Minnie to dance with her (just as she'd asked EVERY other character including Minnie herself at MK the day before, and all were happy to do so) and Minnie, not even very in character, just shakes her head. My friend, a little perplexed says again, "Will you please dance with me?" Well at this point Minnie just flat out ignores her and gets in the Minnie pose and stands still. The PHOTOPASS woman jumps in and says, "C'mon Minnie, dance with her! It's lots of fun, don't be shy!" Minnie does not move from her pose! She's stiff as a board. Well she gets her picture taken with Minnie and walks away feeling pretty dejected. As we were leaving, the Photopass woman says, "I'm sorry guys...Minnie must not feel well today!"
Later on as we were leaving AK at closing time, all the characters were at the front taking last minute pictures and hugs. Well we see Minnie and I say, "Hey! Why don't you try dancing with THAT Minnie, I bet she's..."different" by now." So she goes up to dance with her and.....exact same reaction. She just stiffens up and doesn't move. IT WAS THE SAME MINNIE.
I would like to think that Minnie was just having a bad day, but it was very odd and a little dissapointing.