Bookmakers, like any other business, regularly make errors. Those mainly concern setting the wrong odds on any match – granted, those are more common in lesser leagues and competitions.
If a bookmaker sets the wrong odds, the punter will never benefit from it, as the betting site can reverse the odds and change the odds at which you’ve placed your bets. So, it’s best to avoid markets with clear errors, especially considering bookmakers flag accounts that exploit their mistakes.