I can top all those stories...kinda. I showed up to my long time dentist for regular check up. The hygienist was doing her thing, my mouth wide open, when suddenly said "Oh, did you know that Dr. XXXX has retired?" Huh? She said he made no announcement to patients, couldn't take the emotional outpouring. Well...what the heck was I doing in that office, work in progress, and the dentist who presumably would be overseeing her work not there? There was another dentist in the office, though neither he nor I had ever crossed paths, and didn't that day. The hygienist finished, said all is well, see you next time. Like hell. I signed on with my husband's dentist, no problems.
Long ago after all my teeth but one had been crowned, I determined that paying extra for dental insurance would not be financially advantageous. So far so good, and I floss faithfully!