Home visits for clinical trials... I need help

I am a clinical researcher and am assisting with a trial that does on-site follow up visits. I joined this lab about a month ago and my first visit, was a bad experience. The participant was uncooperative, demanding compensation immediately, started berating us, and was talkative but in an intrusive way. Nonetheless we got out of the appointment and of course dropped this participant, but it was incredibly nerve wracking and uncomfortable. My coworker tried to assure me that this was her first bad experience and that patients are generally calm and very nice. Unfortunately that experience has really affected me. I like my job and the project, I love seeing the participants when they come in the office, but the thought of doing another onsite visit has me holding my breath. How can I get through this and have an open mind moving forward. Will anyone who does on site visits please reach out to me and share some advice? Thank you in advance!