Most people want 8 or younger because they can shape the kid better. If they get aggressive or have problems, its easier to fix and take care of. You also have the joy of seeing them enjoy a new thing for the first time. Ice Cream, Disney World, the Ocean, and other stuff is all new to them.

10-14 are the monster years which mean Bipolar disorder, crazy aggression, and having medical needs but using them to control others. I had one hit on my wife, another peel skin off his foot to get medical attention, and another tried to kill us while we were driving somewhere. You need to be prepared for this, and not think you can win them over by personality alone. If you can't handle them, give up quickly and tell the case workers so you are not stuck.

After that age, they tend to do better, but it's not the same as being the parent the entire time. You accept it's more like being an aunt and uncle who took them in, not the full parent who they've known their entire life. On the other hand, you get a fully-fledged buddy without having to deal with all the previous mess. Talk cars, play videogames, and go places without all of the worries.

The big issue is the foster system itself. The people who work in the Foster program often treat these kids in the same way a car salesman will work his trade. This kid has a newly built engine... They got out of the psyche home. This kid has no aggressive tendencies, just acts up every now and then. Said acting up destroys half the house with no real stop valve. Low miles, the kid has been through so many homes the schools stopped caring who was taking them in that day. Stuff like that.

Then you have the original parents. They can show up unannounced, or sneak phones or other methods to stay in touch with their child. That's a lot of problems because theirs a reason why those parents aren't allowed contact. This can include other foster parents.

We had my wife's cousin over and her twin boys. We called the boys the Daleks because of how destructive they were. We got them those walking chairs, and they moved around like the Daleks. We found out why the entire family told us to beware of the cousin. She slept with a neighbor while drunk and high, stole our stuff, gave it to other neighbors, and did the same with all sorts of people online. Stuff was broken with no real explanation and then blamed on raccoons or the twins. If this had been a foster program, the cousin would have been kicked out without even a question. It made me realize why there are so many rules about parents.

The biggest problem I have is I have no idea how long we will have a kid. It can be a few days to months. There is no warning or preparation. So we have had to be thick-skinned on that issue. Most kids are told to call us Auntie or Uncle from the Hawaiian tradition and leave it at that.