Odd dogs can be (commonly known as a hard breed) German Shepherds, Dobermans and Rottweilers. The more "intelligent" breed such as Border Collies, can also be very sensitive to sounds and fast movement in a club surroundings.
Of course this does not apply to all individuals of the breeds and many do well in class environments.
For owners who are not sure how their dog will react, it is advisable to check with the trainers at their chosen club and, perhaps, sit in with the dog for a couple of weeks, before embarking on a course.
Most clubs should allow you to do this, if not - look elsewhere.