Most of my experiences have been with them touching my pubic hair. My first was during an initial consultation with a urologist before my vasectomy, I was lying on the table with my pants and underwear pulled down to my knees. The doctor proceeded to give me a thorough genital exam that included him combing through my pubes with his fingers.
At my previous dermatologist, he would eventually have me lie back on the table while he and the assistant would lower my gown. They would lower and fold it, exposing my chest and abdomen, so that it just barely covered my penis and scrotum. He would examine me, working his way down until he would use his bare hands to rifle through my exposed pubes. He never actually touched my genitals in any way, but he would look at and touch my hair and skin all the way around them. He examined and looked at my genitals and butt crack, just didn't touch them.
My previous PCP used his hands to examine all of my pubic hair in detail twice. First during my new patient exam, and then at a later exam when I went to him for a lump near my testicle. I was standing with my pants pulled down for both of those.
The last doctor I remember giving my pubes attention, and the only doctor who ever commented on them, was my surgeon who did my bilateral hernia repair. At the initial consultation before the surgery, he asked to see my lump while he squirted hand sanitizer on his hands and rubbed them together. I thought he was going to do the typical hernia exam, so I stand up and pull my pants and underwear down to my knees and lift up my shirt tail. He wheels over on his stool and just looks, for a really long time. Eventually he uses his bare hands and rifles through my pubes, and just looks some more. Never does actually examine me. Eventually, I feel extremely self conscious and just pull up my pants. At the follow up appointment, he asks to examine me. So this time I just lower my waistband a little and lift up my shirt. This time, he actually asks if he can examine my testicles, so I then lower my pants. Of course they shaved me for the surgery, but only shaved the top portion and sides of my scrotum. As soon as I dropped my pants, the surgeon chuckles and said, "Nice shave job".