In fact, it is quite common mistake, especially among users who has very limited knowledge about blockchain and other stuff. For example, ETH wallet address and private key look absolutely different (at least in my view) but that fact does not help at all because one does not know that ETH address starts with 0x. And ofcause one has to always double check when submit the wallet addresses.
There are lots of users that are been scams for that the same mistakes and always stating that Myetherwallet is a scam,
Getting scam on myetherwallet is kinda supper hard for an scammer to do, the easiest way to do is to get the private key itself using fake website such as phishing sites, having these phishing sites around makes once users unsafe on browsing their wallet online, it is always says and advice for all that you should bookmark the right sight to avoid these phising sites and also keeps your private key in safe and secure.
I use myetherwallet as my ERC20 wallet and as of now i never encountered such issues. so I may say myetherwallet is still safe.