proxy's

I know proxy's can be unsafe, but I'm not sure exactly how. What I really want to know is, is a proxy only dangerous while it's running? Can i run it and log in with a character that I won't mind losing and then close the proxy and log in on my main, only putting the worthless account (or my whole computer) at risk until I close the proxy?

the main reason a proxy is unsafe is because all the information is sent from the client to the proxy then to the server,so the proxy has your log-in information,and can also send command to to the client.so its all whats in the programing of the proxy and without the source you can never be sure its safe.Itcould send your log-info to a different place,so they have the info and can "hack you".And theres the possibilty of drop commands when you recive a "special packet" could be a chat(nproxy)packet you drop your stuff.so thoes are some of the main reason a proxy can be unsafe,along with a virus scan tells nothing becaus its programed it-its not a backdoor/trojan/worm.

but it can only steal my login info if i type it in while the proxy is running?