Have you noodled about the forum? There have been many posts and threads about meeting poly-inclined dates. As you know, it is common to be rejected because someone is not ethical non-monogamy. There has also been much discussion of when to tell a potential interest that one is married, and poly. Generally, the sooner the better but one's mileage may vary.
There have been several specific threads about men who are having a difficult time finding people to date even as their girlfriend or wife seems to have her pick. It's a tough situation and one that you are not alone in. I would advise you on how to search for such threads but I am not good at searching myself. Perhaps someone else will point some threads out. But if you poke about, you will find them. They are often in "New to Polyamory" or in "General Discussion".
Many people have noted that this situation is one where fairness, not equality, is good to keep in mind. You may never get the interest your wife does because, stereotypically, the bisexual woman is a 'hot commodity'. However, that fact has diddlysquat to do with you personally. So you may go longer between meeting women with whom you may develop a connection. It's not a competition - as long as your needs are met, and your wife's needs, then it's all good.
As for meeting babes, have you connected with your local poly community? Many places have meetups, local organizations, that arrange events, parties, etc. You may still not find anyone but at least you would know the people there have a passing acquaintance with the idea. OKcupid is also a possiblity. Yes, online dating can be annoying but it's an option. Also, online you can polish your 'game' as my male friends like to call their 'attracting the female' patter and behaviors, before going live, so to speak.
It is entirely possible that your bad vibes about the new male interest are born out of jealousy. It's also entirely possible that he's a douche. And, it's not out of the realm of possiblity, that both are true - you're jealous and he's a douche. The only way to figure it out is to sit with those feelings and start sorting through them. Sometimes it's helpful to tell your spouse that you have a bad twinge about the guy but acknowledge that this might be your own internal thing. Then she has the information of a potential douche alert, that you are uncomfortable but you realize your reaction might be caused by jealousy and/or insecurity. She can then decide to keep a closer eye on the guy, ask what can reassure you, or any number of options.
Finally, and somewhat tongue in cheek, change your user name. 'Nooneparticular' is sad. You are someone, your wife thinks you are cool. Your username should reflect your uniqueness - what you have to offer. If you think of yourself as no one special, well, that's who you will attract - no one special. So pick something from your life that you think is nifty - everyone has at least one thing about themselves that is awesome - and create a username around that. Of course, you also don't need to go the opposite braggart route - i.e. SuperSparklyPenisGOD - but put your best foot forward. (Babes love this.)