This is all you really need to know. Here are just 2 of the many lovely ECCIE providers in action. How could CBJ POSSIBLY compare to that?
http://www.pornhub.com/view_video.ph...h5589dc81a08fe
http://www.pornhub.com/view_video.ph...h55bfd858e2b7b
http://www.xnxx.com/video14477291/chanel_cum_on_face
As for STD risks? Do your research. From the stuff I've seen, it's rare to get something from BBJs. But, like anything related to the hobby, there is still that risk. Do what makes you comfortable. For me, if a lady is CBJ only and I didn't know ahead of time, I just skip the BJ altogether. The visual AND the feeling is ruined. It's a struggle just to keep hard with CBJ for me. But, again, do what you're comfortable with.
Now, go get a blowjob already and stop being a pussy about it. Get you some!