Some of the pros of hookups over long term relationships include ease of communications, compatibility, and being able to meet in person without much fuss or expense.
In some cases, it can be difficult to tell. It's really important to have an idea of how short the relationship will be.
Well, one of the worst ones is that you don't know if you've found the right one.
If there's no way to know which one you should choose, you could always use both options: join a free one and a paid one. You'll be surprised at just how many options are available on the internet.
On the other hand, if price isn't your primary concern, a paid dating app might be just what you need.
For instance, maybe you only care about quality not price. In that case, the free adult dating site would be a good choice.