Re the unfortunate story you mention: This is sad, but doesn’t relate to the issue at hand, whether you are supposed to pay for your plumber, your electrician, your band, your caterer, and your shadchan, or not.
There are unfortunately bad apples in every service industry, and I’ve heard some really unappealing ones about shadchans. For every story, though, I am sure there are countless more of shadchanim who give their heart, soul, and endless hours to a service that seems to be quite underpaid. There are horror stories of band players, electricians, and doctors who’ve amputated the wrong leg. That doesn’t mean the entire industry shouldn’t be paid. It does mean that we need to be careful before we call up a shadchan to enlist his/her services.