I agree that camps can help you see a program/school/coach more clearly. In our experience being from the East Coast, indoor camps can be pretty worthless if you are an outfielder or position player. Any games inside are pretty limiting. PO is a different story. If you're in CA or FL you can take advantage of the winter camps that are plentiful. If you kill it in BP and they need hitters, that can be great as well.
We had a similar to the OP experience with a Villanova camp this summer. We got a personal email from the coach asking my son to attend. He had seen him play numerous times. So, we coughed up the $$. It's close to home so it wasn't a financial burden. What it turned in to was a sham. As mentioned above, no shirts with numbers were given out so there was no way for the boys to be distinguished. Coaches didn't really interact with any of the kids. They just ran the camp and talked to each other. At the end, they basically said don't call us we will call you if we are interested. Needless to say, the 2 other friends we knew there got the same email and never heard from anyone at Villanova. As per PG, they have 3 2020 recruits right now.
I think it's best to find out from the coaches what they are looking for in your son's class. If they don't need infielders and your son plays short, think twice. Agree that if your son has been in contact consistently with any of the coaches, do it.