When I initiate contact with a couple, I try to be explicit that I'd like to chat with both people, for a couple of reasons. One, I think it's respectful, since I would be getting together with a couple, not with a woman who just happens to have her husband or SO nearby (well, I guess there are those situations as well, but I think you get my point.) I think that usually online at least I end up chatting with the man, and I've had my share of disappointment when I figure out that he's just speculating. In fact a couple of times I've met couples where he is trying to talk her into things in front of me and it's kind of embarrassing. So yeah, I prefer to be in contact with both, but I'll still meet a couple usually before I've spoken with the lady.
But my other thing that I want to be sure of is that the man is straight and not closeted bi or gay. I'm not homophobic and don't mind incidental contact (and I probably enjoy it some!) but I did once swing with a friend where we met a couple and the husband was just flat out dishonest about being bi; in fact he was fascinated with my cock. The buzzkill in understanding that he was just dishonest was probably greater for me than him being bi. I just don't like being around naked dishonest people.