OP, as is well known, there's a big difference between a BBBJ (bare back blow job) and BBBJCIM (bare back blow job cum in mouth). Which are you asking about? If you're asking for CIM, I believe that will lower your chances considerably. But if that's what you want, you have been given some good advice by other members, above. In addition to finding good extras clubs, how you present yourself, both physically and in attitude, will play a role in your success.
I don't know where you club, but in all the places I go where extras are available, 90% of the time I get a BBBJ, usually without requesting it, and most often at no extra charge.
I love a good BBBJ and then often like to finish with "covered full service." I've also gotten BBBJCIMs, but there's sometimes an upcharge for that. I used to have a "semi-regular" at the old Follies, and CIM was always included in her VIP fee in lieu of CFS. And she was fantastic at it.
OP, you said, "In the past 7 years or so I've asked like a thousand strippers they do blowjob however it's only condom BJ." Not sure the reason for that with you, but it could be your hygiene or your approach. My success rate is not because I'm special in any way, but I think being presentable, clean and well-groomed, as well as friendly and considerate of the dancers' comfort has helped me.