Sometimes people use text spinning tools or homographs. They would also merge/combine small text pieces stolen from different places, which makes finding the original source difficult. I would recommend searching for short sentences with complex word combinations.

There is one more tool called Plagium - https://www.plagium.com/en/plagiarismchecker
It's actually the only plagiarism web-engine i use when i search for scam ICOs. Results are pretty great, compared to seoreviewtools and edubirdie.
There is a limit to the number of free searches but you can easily bypass it by using another browser. Give it a try.