Ugh. While the right hated her for likely absurd reasons, the left has despised her (and Bill) for very good reasons since the 90s. She is associated with Bill, like it or not. And she both plays that up and plays it down when needed. The Clinton presidency brought in the “New Democrats”, which turned away from the working class, and set their goals on winning over and representing the well-educated class. This meant killing welfare programs, deregulating banks, increasing the prison population, fast-tracking NAFTA, etc.
But for Hilary, I’ll try to summarize a few issues why she has been the enemy of the left for so long: she supported the invasion of Iraq, supports the death penalty, opposed reinstating Glass Steagal, supported every “free trade” agreement, sold fracking globally, supported the Patriot Act, supported DOMA and DADT, supported US militarism and imperialism, considered, is very opportunistic and only changes her position when forced to by overwhelming public support (never leads), bragged about admiring and taking advice from Henry Kissinger, really bad on Palestine, was on the board of Walmart, cynically weaponized faux feminism in order to destroy opponents (like Obama, Sanders), was against free public college, declared that single-payer healthcare will “never, ever” happen, lied repeatedly about opponents positions (and sent Chelsea out to do some more lying), supported private, was very friendly with Wall Street, repeatedly made $200m+ speeches to Wall Street (even when she knew she would be running), took part in red-baiting (Nicaragua, Cuba, etc) during debates, essentially ran the DNC, campaign pushed the “pied piper” strategy in order to prop up Trump, secretly took advance question from Donna Brazile during a debate, etc….
I’m sure I’m missing a bunch of things. But this might give you an idea of why she is so loathed.