When it comes to communicating with another potential couple, we don't spend too much time. If they seem to be a match, we go ahead and set up a dinner (or drinks). You will learn more in 5 minutes in person than you will ever learn sending emails and/or texts. It will also quickly week out the fakers as well. Sure, your are going to go out of a lot of dinners where there isn't any chemistry, but the only way to find out if there is anything is to meet. We look at it as a fun night out for us since we let everyone know that there is nothing more than dinner on the schedule. You have to remember: finding a four way match is HARD. Much more difficult than finding your partner because it's times four. We have met other couples that we thought we instantly clicked with...only to find out for one reason or another, they didn't click back. Don't take it personal, just move on to the next couple. It's a numbers game and eventually you will find a match. Don't invest too much time in non-matches or near misses.
As for why you have encountered men who are duds...most men (IOHO) try to stay on the 'safe' side when it comes to talking. In this climate, talking about sex to a woman (especially one that isn't your partner) can be a very risky proposition. The safe route is to talk to the other man about safe subjects. Most men do not want to come across as crass, or even worse, pigs. We have run across this SO MANY TIMES. Thing to do is to keep steering the conversation towards the group (all four of you) and not having it become 'just the women' and 'just the men' talking. You're all there to find out more about the TWO of them and they of you. The other 'funny' thing is how many couples are afraid to bring up the topic of '...sex' (said in a hushed tone). People aren't supposed to talk about sex with other couples, especially in public...but that's what the four of you are there for. Eventually SOMEONE needs to bring up the topic and let it be known that it is okay to talk about sex. We usually do this by asking about their 'experience' in the L/S. Once this door is opened and they know that its okay, things usually take a much more interesting turn.
Since we have made it known from the start that the first meeting is just a meeting with no play scheduled, it gives everyone the chance to discuss things afterwards. Most of the time there is no spark or connection and we all just go our separate ways, but usually with a bit more knowledge than we had before. Sometimes one couple is interested but the other isn't, but sometimes (and once again, this is a rare occurrence) everyone will want to meet for a second meeting. That's when the good stuff happens...
It's not easy...it isn't supposed to be. We swing, not because it is easy, but because it is hard (okay, I'm paraphrasing Kennedy here, but I'm pretty sure this is what he meant). Once you get through the weeds and chafe, it is worth it. Totally worth the effort and work required!