In my experience, uncircumcised men seem to be more sensitive and, sometimes, a tad nervous about tearing when getting a blow job (understandably, I've seen and felt scar tissue at times). I've learned a few techniques like running the tongue just under the foreskin before it's completely retracted to take advantage of the sensitivity and putting more emphasis on the up movement rather than down so they don't worry that the skin might tear. As givers, what have you tried or noticed? As receivers, what do you like?