I’ve seen it plenty, plenty times. Because I was looking for it. That was my “plan A” strategy when I still bothered dating; it works great as long as you know to be assertive without being pushy. (Some people want to be left alone, some only want to chitchat, both things are fine and you should respect that.)

My “plan B” was relying on connections, but that relies on luck. For example:

• you go to the bar with A
• A is acquainted with B, who’s drinking with C
• You say “hey, what if we all drink together?”

Then you have some room to at least know B and/or C better. And potentially ask one of them out.