There are many different reasons for another country to disallow a person to enter their country. Often times it has to do with legal issues that the person has had in the past. The offenses can be minor or major, it is still up to the country being entered to allow the person to enter said place. What kind of offenses can keep you from entering a country? It can be anywhere from drug charges and even people who have a DUI on their record can be denied entry.
Canada is our brother to the north and they deny hundreds of US citizens a year because they have a DUI on their record. Some may ask why the person would need to go to Canada or just to cancel any travel plans to Canada. This is not an option for many people in northern states as many people who are denied access are there for business reasons. This has led to the termination of multiple people because their employer needed them to travel to Canada for business reasons.
There are even law firms that specialize in entering Canada with a DUI as this has become such a prevalent problem. This law firm at http://www.canadaduientrylaw.com/ gives advice for entering Canada even if you have a reckless driving charge. They have advice on getting a temporary resident permit so you can enter the country for business. This permit can take up to 6 months so if there is any chance that you will be visiting the country for business even in the next year or two then you should apply for one as soon as possible.
Not knowing all the different tips as how to go about getting into Canada with a less than stellar driving tips can leave you stranded at home or even worse it could leave you unemployed if Canada is in your sales territory. The best thing that can be done is to learn all you can about this issue or hire a law firm that specializes in this so you can enter and leave Canada as you please.