I've had mixed experiences. People at planned parenthood have always been really nice and helpful.
Tulane hospital in New Orleans treated me like fucking scum, the doctor actually laughed and made fun of me. I get that they probably see a lot of shit but I am by nature polite and well spoken (thanks, ma!). It was 9am, I was stone cold sober, relatively clean and had a staph infection that needed antibiotics, there was no reason to be an ass.
Another hospital for low income folks (Cooper Green) were pretty nice to me, but also dismissive and ended up making my issue worse. Also they didn't let the local antibiotic kick in before they started cutting into a really sensitive abscess, the nurse had to hold me down while I bit my belt.
Once I went to a fancy Catholic hospital's ER for a really bad staph infection (following the Cooper Green incident), they were amazing. I am not a Christian, I was dirty as hell and really freaked out from all the pain I was in. The nurses kept checking on me, the doctors were really kind. I had to be admitted and have emergency surgery, stay there for two weeks on IV antibiotics. The ER nurses would come up and check in on me and all the nurses / doctors on the floor were really sweet and genuinely interested in the fact that I traveled without money. They never proselytized (try to convert) to me, and even sent someone from billing up to my room to let me know about the different hospital charities I could go through to help get my bills reduced and / or paid.
Maybe the key is to go to a hospital that doesn't get a lot of homeless / traveling folks because they aren't burnt out yet by the folks that make us all look bad.