Wow. What a string of unfortunate experiences for you. Let me make clear that we haven't started swinging yet, but why would people (particularly men) engage in an activity (drinking to whatever excess,) that in many cases has a directly negative impact on the very activity (potency/sex) for which they are there in the first place?
Performance pressure (I would think) would be high enough for us males without chemically increasing our chances for failure. Maybe they drink to not feel the pressure so much, and thus a vicious circle is started. That makes about as much sense to me as being afraid to drive, and intoxicating oneself to feel more comfortable behind the wheel. Anyhow, maybe you should (and I don't know how you would diplomatically pull this off) let potential playmates know of your recent disappointing history, and ask them if they're really good to go, i.e. not drinking to a performance inhibiting extent. NOW talk about pressure!
Then again, maybe not. I guess you just keep trying perhaps.