The phrase "untrustworthy sources" refers to information or people that cannot be relied upon or believed. It means that the sources are unreliable and may provide false or misleading information. Full definition
«Attempts now to rewrite the story of this hate crime appear to be based on untrustworthy sources, factual errors, rumors and innuendo rather than the actual evidence gathered by law enforcement and presented in a court of law,» the spokesperson said. (religion.blogs.cnn.com)
I wonder however if there is some truth to the analogy that «beta cells can become «tired» from working overtime» (as I heard from some rather untrustworthy sources)? (nutritionfacts.org)
We should most certainly take this with a very large grain of salt — anyone can say anything on Twitter — but this is neither a wholly untrustworthy source nor an outlandish rumor, so it is at least worth considering. (nintendoenthusiast.com)