For me a bj, just like sex, is just as much visual as it is the actual physical act. So if a lady's a 3 on a scale of 1-10 it doesn't matter if she can suckstart a lawnmower, I'm not gonna get turned on.
I mean there are probably some trannies out there who can suck the paint off of trailer hitch but I'm not going to let one anywhere near my cock.