Previous clans

In all honesty I believe there should be a feature that lets us see previous clans of people joining and if they participated in war or not. Yes the new goal shows you how many stars you've received in battle but that doesn't always mean you've participated in every clan war. But back to the main idea there are now "spies" coming from clans you're in war with on preparation day and even just people wanting to be mean and leaving as soon as you join a war. It's ridiculous. There needs to be at least something to control that besides the "closed clan" because it's obviously not working for us. Any suggestions for in the mean time would be greatly appreciated.
Clan: Red Dragon
Leader: BushidosQueen
Thanks in advance. 😄