Raymond Burr is quite heavyset in some episodes, but he is still cast as the heroic leading man. It just goes to show how different standards about body image were back in the days that Perry Mason was made.
It seems that nobody on the show remembers their fifth-amendment rights. The murder almost always confesses on the stand, except when they confess when they're not on the stand. (Actually, while I was writing this, an episode showed where the accomplice ratted out the murderer... but this is the exception to the rule.)
Berger is like the worst district attorney ever -- he never wins a case, and never accuses the right person. Not to mention the detective, Lieutenant Tragg; his theories of the case are always wrong too.