Football betting takes up a lot of my time but I would never place a bet on a new manager market.
In answer to the question "Do bookies get it wrong?" it depends what is meant by wrong. It is normal to have at least three different names as odds-on favourite before the actual appointment is made. But that is hardly getting it wrong, it's making money. As others have said "new managers" are small markets normally, if a large sum is staked (or more likely attempted to be staked but a smaller sum accepted) the bookmakers will soon reduce the odds drastically or stop taking bets suspecting someone really does know something.
So far Neil Harris has been the only odds-on favourite and he may well be the new Cardiff City Manager, but if he is it will be a rare occurrence of a man leading the betting all the way. More often a name from the pack or even a name no-one has mentioned comes through to get the job. Here's hoping it's Mr Craig Bellamy.