That would not be a good idea.
I have a tatoo.
I give blood. If you don't want my o neg because it might be contaminated (it ain't) then you can bleed out and die for all I care, Darwin will not be denied.
I don't have a tat, but most of my friends do. Our local tatoo artist gives the needles he uses to the clients after he inks them, so no contamination. I'd rather get blood from my friend Leti (has a tat in honor of her deceased baby broter) rather than a gay guy who isn't celibate and doesn't pracice safe sex.