Specifically, my point is directed to telegram users who are Bounty and Airdrop Hunters, it happens many people tell people about hiding their usernames without speculating the impact clearly it's true that hide username will only let you to the channel or group you want/participate
But if you think clearly you will see the probability of meet different projects will be very low as sometimes its happen to be added to some group which is a benefit to us, I think Bount or Airdrop hunter should not hide their username let them Add you and you will see if project profitable to you or not then make decisions to leave and report it.