My husband was/is a Science teacher. He did well at his first school, and he was promoted to be a key stage 3 co-ordinator in the Science department when I was expecting DD (in 2007.) Then when I became pregnant with DS, he got a job as a second in the Science department. DS was born May 2009, my husband started his new job September 2009.
He was made aware very early on his face didn't fit, and he didn't know why. He is a very mild mannered man (when he isn't watching girls play volleyball!) and I can't think of anything he would have said or done that offended people. He had a really difficult year there, where he felt nothing he said or did was right. If he ever told a child off or sent them out he would be questioned and on one occasion even had to apologise to a child for "touching him" - all DH had done was put an arm out to stop this child barging out of the classroom!
In September 2010 he was observed and was found to be inadequate. At this point, lots of other "evidence" was found against him, and honestly you wouldn't believe the lies - it was horrible. He agreed to leave and did so at Christmas. He actually got a job as Head of Science in January 2011, he's just been promoted again to be an Assistant Headteacher.
He has always claimed he doesn't even think his lesson was a bad one, they just twisted things so that it was. It was an awful time, I'm glad it's behind us both but don't ever believe that it's hard to sack a teacher. It might be hard to dismiss, it certainly isn't hard to throw someone out via the side exit!