Don't call me a weirdo it's just the way I feel about this, if your key is lost and I don't have a way to get it back then it will remain is its lost state, if you spread the news and give your keys out for recovery and they denied they don't recover them what will you do?
I don't get the point of the question,
is it in case the recovery service recovered the key from the wallet, spent the funds but told the owner that they failed?
If so, it's easy to tell if the funds were spent because the user can always check the funds through various blockexplorers or using a 'watch-only wallet' made from the bitcoin address.
If that happens, you can create a scam accusation thread with enough evidence like screenshots of the wallet and conversations, etc.
Most of the time, it's enough to crush a service's reputation.