I think it does make a difference. I had my first rectal exam when I was 20. I was constipated and went ti the student medical center expecting to be given laxatives or an enema. I wasn't expecting a rectal exam. I was made to bend over the table and in went the finger. It was very uncomfortable, even with ample lubricant and the doctor repeatedly telling me to relax. It was only after he took his finger out that I realized that my legs and butt were tightly clenched and I was holding my breath the whole time. Nowadays, my urologist always has me point my toes when I bend over, with my legs apart and knees slightly bent. He also instructs me to take deep breaths through my mouth. I find that although my sphincter tightens reflexively after anal penetration, this lasts for only a few seconds, and for the rest of the exam, it completely relaxes as if I was taking a poop. It makes things a lot easier for both of us, since he often needs to be in there for quite some time in order to massage a prostate sample. Yes, you do feel completely exposed during the exam, and you can't hold your farts in this position.