Why do people who adhere to political parties like to paint opposite parties with a broad brush?

Republicans say, ';Those Democrats are all losers'; while Democrats say, ';Those Republicans are all a bunch of pompous jerks.'; This tendency of both sides is beginning to make me sick. People need to start thinking for themselves instead of being loyal to some party.Why do people who adhere to political parties like to paint opposite parties with a broad brush?
wrong place for the question but I'll go with your metaphor. A broader brush is clearly less detailed. They don't really see what their opponents truly are. They aren't interested in knowing who and what their opposition is so they don't try to see them clearly and thus use less detailed means when recreating them. Perhaps, also a subconscious thing. The human tendency is to fear the unknown and by blurring the picture it is less ';knowable'; (it's a word now dang it) and thus something to be feared, not trusted. Why do people who adhere to political parties like to paint opposite parties with a broad brush?
Good question, but miscategorized.