You have said it all and i have always tried not to fall for such scams, they are all over telegram, some of them carry out pre-sales and ask you to buy their coins by paying with ETH etc (most if not all of these are definitely scams), some even ask you to pay to withdraw, why can't they just remove the charges during withdrawal? i prefer to go to binance or coinmarketcap to check for airdrops because they all are legit.