You develop an eye for it eventually. Some people unavailable, some are just not interested that night, some are hostile. These things change through the night so someone that was hostile earlier might warm up or become friendly over time. The body language is Usally a good tell.

They are also other signs that hint towards compatibility such as wealth, class, education, social anxiety you get a feel for it over time. I would trust that over what you see in a profile. Not that you can’t lie on those just that it’s much harder. Plus The dark things people tell you after a drink or 2 would often be enough to get one cancelled off the internet.

Also keep in mind that a lot of people screened themselves out just by not going out. All those gals that don’t have anything money, live with their parents and go to bed at 9 or have no friends. You won’t find them at the bar but on tinder you might