Note that some sellers will cancel your bids if you have private feedback, because this is all too often used by scammers who want to hide the evidence.
The main people who will be interested in your purchases are your friends and family. Don't tell the your username. Always log out after using a shared computer (you would be amazed how often I have been directed to another member's account while using hotel computers!). Don't tell anyone your password.
Your computer may have a Private Window function which will not show your browsing history.
And since there is no limit on the number of accounts you have, you could just have one account that you keep secret.
But as for feedback, nobody is really all that interested in you.
