They showed up for a sub $1/a cup coffee. I doubt there is much malicious intent.
If some of them do so more because the free coffee is that valuable to them, what's the downside with letting them have the free coffee you wanted to give away anyhow? Imho that would be a good opportunity to get them more support, not a problem with that approach.
The "trick" to it, in regards to dating opportunities, is the place has to be quietly accepted as a "safe" hookup spot, as well as have a good setup for people to move around and talk to each other. What I mean by setup, is the design of the place. Like having lots of benches or chairs in a row or parallel to each other, not facing (can make people uncomfortable when approached by strangers) or far across from each other (which can cause yelling as hard for people to hear each other), where people can easily sit next to each other. It also must be accepted or encouraged by the staff, managers, or owners that people there, even though strangers, can approach and talk to each other. Bad behavior is not accepted, but polite talking is.
It's tricky, because women will avoid or condemn a place that gets a bad reputation (which is easy to create on social media), be it deserved or not. The place has to be considered safe, cheap, respectful, welcoming, and fun. The combination of such appears hard to get right, so can be hard to find. Places that are good for such socializing, can also be surprising and unexpected ones. And when people do find them, they tend to be quiet about them, to avoid it getting a bad reputation (which can ruin it).
Many places that seem like they could or should work for socializing or hookups, often are actually bad. Be it the design (separate tables that are far apart) or the environment that's created (talking to strangers discouraged). For instance, if those managing it or owners are overly protective or strict, then people may come just and only for say the coffee. No talking to others, drink up, then leave or be nearly completely absorbed into a computer or smartphone. The environment, which encourages and allows polite socializing, has to be created and maintained.