Email scammers in general.
Their lack of English abilities has saved me more than once from an OPSEC mistake!
TRUE! I was also saved couple of times! But there are also good scammers with I dont know how, but their e-mails looks sooo legit and one time they had a LIVE support chat ZenDesk. Everything set and ready to steal your money. And it was the only case where the language were perfect! Mine not!

)) I know.