Are all used car dealers scam artists?

I'm looking around for cars, trying to do research on dealerships. Every one that look I up has negative reviews(Don't buy from here..rip off..scam! etc") along with one or a few positive reviews. I'm sure that not everyone who has a great experience writes a review, but should the negative ones dissuade me from buying at that place? Is it all just hit or miss with these places?