Why can't Republicans sell their ideas to the American people without resorting into doing dirty politics to win elections?

Democrats do politics dirty as well but not in the same level as Republicans. Is it because Republicans just couldn’t sell their conservative views and vision to voters unless they incite hateful rhetoric which is exactly what Trump used to get attention and win?

Is the future of America liberal by nature? And conservatism as represented by Republicans a lost cause desperately defended by Republicans using shitty and self-demeaning politics?