Thanx for your answer.
Yes i tried to do same and even use '&expand=password' REST feature to force retrieve password but without success :(
btw i do it with Super Administrator rights.
But SOAP returns it without any problems.
I know there is a special setting (disabled by default) to let Admins see the guest password.
Seems i have this option is turned on, cause now i can see it on my GUI (see screenshot)
2. Just i have desktop client which is using SOAP API and customer want to get rid of it to use REST API instead of (he afraid SOAP to be removed for further releases).