I think this is a great idea slash, but it can only apply to the GA section.
I have 4 users on my TL invite tree that have never used their account after me giving them free invites, they begged me to invite them and now they don't answer any PM'S.
I also have had many accounts ban because of ratio cheating idiots, I think a rep system for invitee's would be great.
After a certain time period you rep them on how they are using their accounts, this would make it safer to give invites in the GA section and cut out the bad users.
A lot of members here are applying for free invites then trading/selling them on other forums, I myself have stopped my GA's because of these idiots.
This system would also log what invites a member has received on TI so there's no chance of them applying for the same tracker in another GA in the future.