I don't buy the premise.
There are more than two sides to almost every issue. And within any side there are opinions and perspectives that I respect, and those that I do not respect. What I tend to hate about opinions, right or left is the following:
-Doesn't acknowledge empirical facts
-Doesn't know the nuances and details of the issue
-Doesn't acknowledge the weak-points in their argument or state their assumptions
-Can't back up their beliefs with a logical argument
-Generally making radical or extreme statements
-Ignorant of history and intellectual basis for their position