We're a couple and there are non-profile things couples have done to turn us away including.. meeting one on one and wanting to talk for four hours and we learn non-sexual things about them that make us opt-out. If they gossip or say bad things about another couple, If in their emails they lie about what they're really seeking- for example they say they want mfmf but you meet and they are unicorn hunting for your wife and expect you to sit in the corner and just watch. And.. lastly.. if one of them gets super drunk at the start of the meet and can't function. That happened once- the wife passed out 60 seconds into fun time.
With respect to guys, we've met some great ones and some not. For them we like ones who have certs.. or we meet at a meet and greet. We've been burned by one on one meets with them for all the reasons people already know :)