The only two countries that I've had difficulty entering on business trips are the US and the UK. In my experience they appear to be concerned more with people having recourse to public funds and jobs rather than terrorism.
There's something particularly arbitrary about the process at the US border though. I've traveled to the US for meetings from Vancouver, Toronto, and Montreal and I've been refused entry twice -- both in Vancouver (which is also my home town). The reasons weren't entirely clear but at least one of the times they had simply left me sitting until there were no more flights. The other time there was an exceptionally high number of people detained so it's possible they were concerned with something else altogether.
re: the beard. Young beards are probably interpreted as an indication more of slovenliness than extremist sympathies. It's part of the mandate at the US and UK borders to weed out the cunning, young beards in seek of a fresh, clean-shaven start.
Honestly, the beard thing has nothing to do with religion. Immigration officials, like all minimum wage dictators (and most people generally, unfortunately) still often have the mistaken impression that suit and tie = money, bearded and scruffy = poor. It is a whole other question why some of the worst paid people feel such a need to look down on others.
There's something particularly arbitrary about the process at the US border though. I've traveled to the US for meetings from Vancouver, Toronto, and Montreal and I've been refused entry twice -- both in Vancouver (which is also my home town). The reasons weren't entirely clear but at least one of the times they had simply left me sitting until there were no more flights. The other time there was an exceptionally high number of people detained so it's possible they were concerned with something else altogether.
re: the beard. Young beards are probably interpreted as an indication more of slovenliness than extremist sympathies. It's part of the mandate at the US and UK borders to weed out the cunning, young beards in seek of a fresh, clean-shaven start.