No. But, I spent much of my life doing so. However, even when working as a mechanic I would make sure my hands / arms were always completely spotless at the end of the day.
I used to but they started demanding to scan in my driver's license into their database. I said no. Then they made a real issue about checking it 15 times while giving blood and then saying if you let us scan it in we wouldn't need to check your ID so much. So, I took that as they no longer wanted my extremely rare blood.
No. But, I've been knocked unconscious several times. Looking at blood and guts doesn't bother me. I've always watched what the doctor cuts/sews up/fixes on me.