I have an opposite take on BNI. I am not in BNI, but my husband has been in the same BNI group for 5 years, and I see it as a very positive organization. He has built his electrical service business almost entirely from BNI referrals and the network that has grown out of those referrals.
There is an approval process for members by the current members. There is no benefit for the existing members to accept unethical members because they too will be referring their clients and friends to these people. They have had some "duds" in the group, but the group has about 30 members, so even a handful of non-participating members or members you don't want to do business with should not limit your networking capabilities too severely. When my husband does not like someone in his group, or thinks they're shady, he simply doesn't do business with them or give them referrals. You are supposed to give referrals each week, but not to every single member. Just refer the ones you are comfortable with. Eventually, the bad members will not get referrals from anyone and will leave the group.
Just an example of the capabilities of the network. . .I believe dues are about $400/year. If you are an accountant, one new client's personal taxes would pay for your membership. For a house cleaning service, that could be 1-2 months cleaning for ONE new customer. The biggest commitment isn't the money. It's the time. The groups do meet weekly, and they are strict about attendance. Still, shouldn't everyone spend 1 hour/week marketing their business? This is a pretty easy way to do it, if your business model is well-suited to local networking.
So I don't appear completely biased, I will say there can be a lot of drama. As with any group of people, cliques can form, or someone in a leadership role can be on an ego trip. I think my husband personally likes the drama a little, since he doesn't have coworkers this adds a little taste of office life to his day.