I have had a mechanic tell me 'that ball joint needs to be replaced' when I've actually just replaced it. Pissed me off big time. You do need to have the recc of a mechanic you can trust
Some play is normal, just not very much. It's been a while, but from what remember you need to jack up the vehicle to get the load off the joint, and then pry it back and forth, preferably with a dial gauge measuring things
Now I have had a ball joint worn enough to separate on me while driving and that's not fun. Luckily was going pretty slow